Mortal Once More

30th July, 1981 

When the Dark Lord had demanded to know why he was late, Regulus had taken a deep breath and, as he looked into those pitiless red eyes, made his mind go blank. It had been somewhat of a relief, in fact, not to think, after everything that had happened over the past few weeks. It seems that the Occlumency he had been teaching himself since he was thirteen had been more useful than Regulus could ever have imagined. 

His mother was a skilled Legilimens, and had often clawed her way through Sirius’s mind when she thought he was hiding something from her (which, of course, he always was). Regulus still remembers how his brother had always been left white and shaking for hours or even days afterwards, every time Walburga had done it. 

She hadn’t often targeted him the way she targeted Sirius, believing she’d already bent him entirely to her will - but there had certainly been thoughts and feelings that Regulus had not wanted his mother to be privy to. His loneliness without Sirius, the way he missed him. His bitter jealousy about Sirius finding new friends and a new family. His anger and resentment at his parents for hurting his brother, for driving him away so that Regulus had nobody. 

So he had secretly set himself the task of mastering Occlumency, often staying up for hours into the night in the Hogwarts library or the Slytherin common room. Nobody had known about his determination to protect himself, to ensure that his mind was private and nobody could claw through it against his will. 

Face to face with the Dark Lord at Malfoy Manor, he had lied smoothly, without even thinking, claiming that the Auror Moody had spotted him just as the Mark burned and he’d had to evade him. He’d waited, heart pounding, for those red eyes to burn into his mind, for that cruel mouth to hiss, “Liar.” 

But instead, the Dark Lord had simply cocked his head slightly, considering him.

“You have been useful to us, Regulus,” he had murmured. “And so you shall not be punished this time. But be warned…” he had raised his wand slowly, threateningly. “The Dark Lord shall not be so tolerant of your tardiness a second time.” 

As it transpired, Pettigrew had not reported him - at least, Regulus assumes so, given he’d somehow escaped from Malfoy Manor entirely unscathed, physically at least. In fact, he had simply been summoned because he was required to go on a mission with Malfoy, Dolohov and Macnair the following week. Something about ‘keeping an eye’ on a senior member of the Ministry, who seemed suspicious about Malfoy and had been deemed a threat, especially if he was given the chance to whisper in Crouch’s ear. 

But he had scarcely been listening to the details. When he’d finally been allowed to leave, almost choking on his own disgust as he had forced himself to walk backwards from the room, bowing to the Dark Lord just as Pettigrew had done, Regulus had practically run back out into the garden of Malfoy Manor, hastily making an excuse to Narcissa when she’d asked if he wanted to stay for a drink. He’d been desperate to Disapparate back to Grimmauld Place, to be alone, so that he could just think.

But now here he is, alone in his room, and still none of it seems to make any bloody sense. Rosy pink light tinged with gold is slowly beginning to filter through the curtains - Regulus suddenly registers that he must have been pacing back and forth across his little bedroom for hours , without even realising. Well, now he knows how Lupin must have felt the other night, he supposes - too many thoughts, too many fears and worries to work through, nowhere to go until he’s tried to make sense of it all. 

Pettigrew hasn’t reported him. Presumably, that means that somehow, he still doesn’t know Regulus has defected. But why doesn’t he know? After all, he’d certainly seemed to know who was going on that guard duty mission, exactly where they’d be and when they’d be there. 

He remembers what Sirius had said to him last night. “Don’t take it too personally, Reggie - I don’t trust anyone these days.” Is that why he’d neglected to tell Pettigrew about Regulus? Because he was suspicious of his friend - rightfully, for once? 

Or was it simply that, amongst everything that had been going on - the Potters going into hiding, his struggles with Regulus and Lupin, and now dealing with the Horcrux and the news about Gideon - it had not even occurred to Sirius to confide in Peter Pettigrew? 

Regulus remembers how he’d seen his brother rolling his eyes at ‘Wormtail’ countless times at school, heard him teasing his friend and putting him down much more bluntly than he ever did with his precious Lupin and Potter. Even the other week, when Sirius had burst in on Dumbledore, Regulus and Lupin without permission - he’d rolled his eyes and made an offhand comment about Pettigrew, how he wouldn’t have been able to stop him, even if he’d been there. Regulus knows, of course, better than most people, that his older brother can often be thoughtless and arrogant, casually cruel and dismissive without even meaning to be. But surely, that alone can’t have been enough to drive Pettigrew, one of his oldest friends, to do… this? 

Now that Regulus thinks about it, though, there had always been a slight edge of desperation in the way Pettigrew had trailed after Potter, and Sirius, to a lesser extent. Almost as though he didn’t exactly want to be their friend - he needed to be, because their reflected glory afforded him some measure of protection and popularity, despite his own obvious mediocrity. Perhaps it was inevitable, in the end, that after the four of them had graduated, he would eventually decide that he wanted to attach himself to other people, people he believed could provide him with better protection, more power. Perhaps Sirius’s dismissive treatment of him wasn’t the cause , so much as just the excuse that Pettigrew was using to try and justify himself.

And even though Sirius clearly looks down on Pettigrew -  without even realising, probably- he’ll still be devastated when he finds out. Regulus knows that much. Regardless of the frictions that might exist between them, those four had still seemed utterly inseparable at Hogwarts. The silly nickname they had given themselves - derived from some private joke between them, Regulus had always assumed - had stuck with other students, and even the teachers, who were constantly laughing, complaining or gossiping about ‘the Marauders’. Those four boys, a collective unit. 

This will destroy them, Regulus realises. All three of them - Sirius, Remus, James. Perhaps even all four of them, even if Pettigrew had already started down the path to self-destruction a long time ago. Their childhoods, their trust, will be shattered with this one revelation. 

But they still need to know - Sirius more than anyone. If Regulus doesn’t tell him, he knows his brother’s trust in the man he loves will just keep crumbling. He’ll keep lashing out, growing more paranoid about Lupin by the minute - which is probably exactly what Wormtail has intended all along, Regulus realises, stunned. 

A small, sly voice speaks up at the back of his mind, rearing like a snake.

And why would Sirius believe you?

After all, Regulus had tried to reach out to his brother just last night - only to be told that Sirius didn’t believe anything he was saying. Just to learn that Sirius still thinks he is the most likely spy. 

Suddenly, he feels as though the walls are closing in on him . If Regulus goes running to him now, after what Sirius had accused him of only yesterday, claiming that Pettigrew is the spy, not him, he’d seen him - why wouldn’t Sirius assume that he’s lying, pointing the finger of blame at someone else to save himself? It’s not as though Regulus has any proof that he’d seen the man at Malfoy Manor, other than his own word - and Sirius has already made it very clear that he does not consider Regulus’s word to be a very reliable source. 

He freezes for a moment, his heart pounding like a frantic bird trapped in a cage. What the hell is he going to do , if his brother just...refuses to believe him? 

You have to tell him, a voice in his head answers, quiet but determined. You have to try. 

Regulus blinks for a moment, willing the nausea to settle as his head finally stops spinning, his knees in contact with the hard stone floor in Grimmauld Place’s basement, the roaring sounds of other fireplaces and the confusing chatter in the rooms beyond them still echoing in his ears. 

“Sirius!” he calls hastily, before he can lose his nerve, spluttering a little as he accidentally inhales a bit of ash.

His brother, who had been sitting alone at the little living room table, perusing today’s copy of The Daily Prophet with a disgusted grimace on his face, jumps violently.

“Reg?” he asks, sounding astonished at the sight of him. He immediately puts the paper down, frown deepening as he approaches the fireplace and kneels down in front of it. 

“What’s happened?” he demands. “You look like shit,” he adds, before Regulus has a chance to answer. 

Regulus rolls his eyes.

“I didn’t get a lot of sleep,” he huffs impatiently. “And I need to talk to you. Obviously.” 

“What did Voldemort want?” Sirius asks immediately, his eyes wide. “Does he know? About you?” 

Regulus can’t stop himself from wincing a little - he wishes his brother would stop doing that, throwing the Dark Lord’s name out so casually, as if it’s no big deal. It’s easy for Sirius to feel brave - he’s never had to stand in front of the man, wondering whether the Dark Lord has seen through the lie he’s just told, wondering if he’s a split second away from being tortured, or worse. 

“No,” he answers shortly. “He doesn’t know - he just wants to send me on some stupid mission with Malfoy and Macnair next week.”

“What -”

“Look, this isn’t about me,” Regulus presses on hastily, not keen on detailing exactly what that mission will involve. “But I found out about something else. It’s…it’s big, Sirius. It’s huge. And I’m…I’m sorry, but you’re really not going to like it.” 

“For god’s sake, Regulus,” Sirius snaps, glaring at him now, his face pale. “What the hell are you on about?” 

He hesitates, his throat suddenly clenching with anxiety. 

“I…are you alone? Or is Lupin home with you?” 

He’s not sure he can stand to shatter both of them at once - that’s if they even believe him, of course. And Lupin already has plenty of reasons to hate him. 

“No, Remus isn’t home,” Sirius growls, a dark cloud seeming to pass across his face. “He hasn’t come back home from his mission yet - full moon last night.” 

Ah. So Regulus’s guess had been right. 

“I’ve barely seen him over the past few days, actually, he’s been so busy preparing, and following orders,” his brother adds, with a small shrug. He’s trying to sound nonchalant - but Regulus knows better. 

“So you’re alone?”

“ Yes, ” Sirius answers impatiently, narrowing his stormy grey eyes at him. “Why? What does it matter?”

Regulus takes a slow, deep breath.

“Stay right there,” he tells him firmly. “I’m coming over. You need to hear this.” 

“I need to hear what? Reg, for god’s sake…”

But Regulus isn’t listening. He withdraws his head hastily from the fireplace - coughing only a little - and waits a few seconds for his head to stop spinning again. 

He stands upright, casts a quick look around to make sure his mother isn’t on her way down, and grabs some fresh Floo powder from the little pot on the mantelpiece, throwing it into the fireplace so that the flames roar, turning a bright emerald green. He steps fully into the fire this time, muttering the address of his brother’s little flat in Camden, and closes his eyes as he begins to spin through the flames, hearing other fireplaces roaring past. 

He clambers out into Sirius’s living room a moment later, still slightly dizzy, absentmindedly brushing a bit of ash onto his brother’s carpet. 

“What the hell is going on, Reg?” Sirius asks angrily - hastily stepping back a little so Regulus doesn’t collide with him. “What’s so urgent? You said Voldemort doesn’t know about you, so it can’t be about the sodding Horcrux -” 

“No, it’s nothing to do with the Horcrux,” Regulus cuts him off, flinching a little again at the sound of the name, and noticing that the golden chain of the locket is still glinting around his brother’s neck. “It’s…” He hesitates, desperately racking his brain for some way to break the news gently. But there’s no easy way to say it, he realises. He takes a deep breath, as Sirius stands there with his arms folded, glaring at him.

“I know who the spy is, Sirius. I know. ” 

Sirius’s glare fades. He stares at Regulus for a moment, face very pale. He swallows, turning his face away, just as he had done the night before - but Regulus can still see the pain twisting his expression, making him look strangely gaunt. Sirius sucks in a deep, shaky breath of his own. 

“Yeah. I think I know, too. I…I think I’ve known for a while, deep down. I just…couldn’t bear to…” 

“ No, you idiot, you don’t know!” Regulus says fiercely. “You don’t have a clue ! It’s…it’s Pettigrew, Sirius.” 

Sirius whips his head around to stare at him again, his face as blank and shocked as if Regulus had just punched him in the stomach without warning. Shit. So much for breaking the news gently. 

“What did you just say?” Sirius whispers, finally, after a seemingly endless silence. 

Regulus swallows. 

“I said that the spy in the Order is Pettigrew.” 

“ Wormy?” Sirius breathes. 

Regulus can tell from the look on his face that, just as he’d expected, Sirius had barely spared a thought for ‘Wormtail’ at all - until now.

“Yeah. Him.” 

“But…why would you say that?” Sirius croaks. “How do you know…?” 

“I saw him at Malfoy Manor,” Regulus replies bluntly. “Last night. He was having an audience with…with the Dark Lord. He was just on his way out.” 

“But he can’t have been!” Sirius exclaims. “Pete was at the Order meeting last night!”

“And did he arrive on time?” Regulus asks quietly. 

Sirius blinks at him for a moment, stunned. It seems to take him a moment to remember how to speak. 

“Well…no…but he told us in advance that he wasn’t going to make it for the start of the meeting…because he’s been working late…”

“He’s been saying that a lot recently, hasn’t he?” Regulus asks. “Isn’t that why he missed the last few meetings? Because he was ‘working late’?” 

“Well…yeah…”

“He works in the Ministry, right? Has anyone actually confirmed that he’s been ‘working late’ with any of his colleagues? That shouldn’t be too difficult, right?”  

Sirius stares at him, and Regulus watches as the last bit of colour drains from his face. It had never even occurred to his brother to think twice about the - rather flimsy - cover story, Regulus can see that. He hadn’t ever considered Pettigrew interesting enough to bother questioning him. 

“You don’t mean…” Sirius whispers.

“Yes, Sirius, I do mean,” Regulus says firmly. “Pettigrew has been passing the Dark Lord information on the Order. He must have been reporting to him for weeks now, if not months - he’s just been telling you lot that he’s been ‘working late’ whenever he’s had a conflict of schedule , and apparently none of you had any follow-up questions for him! Your busy little friend , Sirius, is the reason the McKinnons are dead! The reason that the Meadowes woman is dead, the reason that Fabian’s brother is dead!” 

He feels another sharp twinge of pain as he remembers the look on Fabian’s face, remembers what Sirius had told him about Fabian’s suspicions only last night. But he forces it to the back of his mind - he can’t afford to dwell on that right now.

Sirius clutches tightly onto the arm of the chair in front of him, his knuckles turning white. He’s taking shallow, shaky breaths, looking as though he might pass out. 

And yet, Regulus thinks that he can see a hint of something else in his brother’s expression, beneath the horror and shock. A tiny glimmer of something that almost looks like…relief. 

He was so terrified, Regulus realises. He was so scared that it was the man he loves. 

But when Sirius looks back at him, his expression is wary again, the grey eyes so similar to his own narrowed in suspicion. He can tell how afraid Sirius is of giving in to that relief - because how much further does he have to fall, if Regulus is wrong?

“I…how do I know you’re not lying to me?” he whispers. 

Regulus had spent so many hours worrying over how to make Sirius believe him. He’d thought that, as soon as his brother said something like this, he would immediately recoil into himself, feeling guilty, hurt, small. 

What he hadn’t been expecting was to feel a sudden, fierce and boiling explosion of anger in the pit of his stomach, bubbling over, making him practically see red. His nerves are stretched to breaking point just as much as everyone else’s - and he’s had just about enough of this.

“Oh, for fuck’s sake, Sirius!” he yells, louder than perhaps he’s ever yelled in his life before. Sirius jumps a little, looking alarmed. “Look, I know you don’t trust me, I know you hate me - you’ve made that perfectly clear. I get it, alright? But I was there, I saw Pettigrew at Malfoy Manor with my own eyes! I’m not lying, I’m trying to bloody help you! I’m trying to stop you from making another stupid, reckless mistake that could ruin your life, Sirius, because you’re too stubborn and blind to see what’s right in front of you!”

Sirius stares at him, his expression thunderstruck. He seems, for once in his life, to be speechless - temporarily, at least. 

The yelling had helped a little, but Regulus can still feel the vestiges of the sudden flare of rage. It isn’t like him to lose his temper so completely like that. That’s always been Sirius’s move. He closes his eyes for a moment, trying to calm himself. 

“Look,” he says more quietly, making an effort to contain himself. “If you’re not prepared to take my word for it - why don’t you just confront him about it?” 

“What?” Sirius asks weakly, still looking a little dazed. 

“Confront him,” Regulus repeats. “I’ll stay with you, I’ll help. He saw me too, last night - obviously - but he didn’t seem to have a clue that I’d defected. Seems not even a spy can know everything. Slipped your mind, did it?” 

Sirius gazes back at him, and he sees an uneasy flicker of guilt in his brother’s eyes. 

“I thought as much. But if you don’t believe that I saw him at Malfoy Manor - why don’t you just invite him for a chat, see how he reacts to seeing me here? That should tell you everything you need to know, shouldn’t it?” 

For a moment, Sirius simply stares at him. The billowing silence seems to last forever. 

Then, suddenly, as though a switch has been flipped, Sirius reaches down, without looking away from him, and begins rummaging in his pocket. 

“What are you…? Regulus starts, bewildered. 

He trails off, as his brother pulls out what appears to be a small, tarnished mirror. 

“Prongs?” he calls into it, holding it up in front of his face as though checking his reflection. “Prongs!” he repeats, more urgently this time. 

Suddenly, Regulus hears a small child giggling, so clearly it sounds as though the little boy is in the living room with them. He frowns for a split second, looking around, before realising that the sound is coming through the mirror in his brother’s hand. 

“Ow…Harry, no,” says James Potter’s voice, sounding just as loud and clear as the child’s. “Padfoot wants to speak to Daddy… what , Pads?” he asks, sounding a little impatient. 

“Something’s happened,” Sirius mutters tensely into the mirror.
“What is it?” 

“It’s…it’s big,” says Sirius, looking as though he doesn’t know where to begin. “No, it’s huge.” 

Regulus hears Potter heave an exasperated sigh. 

“For god’s sake, Pads, what are you on about?” he huffs. “If this is about another row you had with Moony, or with your brother…”

“It’s not,” Sirius says shortly. “It’s…” he trails off. “Look, I’m coming over now, okay?”

“What?” Potter asks blankly. “Right now? Pads, wait a sec, Lily will -” 

Too late - Sirius has already Disapparated from the flat with a crack , taking the little mirror with him. 

Regulus stands there, staring at the spot where his brother had just been, wondering how on earth Sirius is going to explain any of this to Potter. James Potter, who seems to have such an abundance of trust and loyalty and affection for everyone, and most especially his friends…

Well, that ought to be a painless conversation, Regulus muses wryly. 

He begins pacing up and down the now deserted living room. He can feel a tangle of anxiety twisting and tightening in his chest as he strides aimlessly back and forth, trying to calm his breathing. Regulus can’t help but wonder how exactly Sirius is passing on the news; are he and Potter deliberating, even now, the likelihood that he’s lying about Pettigrew to save his own skin? 

Now that Sirius has left and the little flat is empty except for him, Regulus realises that being back in this living room is making him feel even more uneasy. He can’t stop himself from picturing the way Sirius had lain on that sofa for hours, completely still; and now here he is again, helpless to do anything but wait for Sirius, not knowing when - or if - his brother will come back to him. 

“Hurry up, you bastard ,” Regulus hisses to himself. 

He jumps as a loud, telltale crack echoes through the little living room a moment later. 

“I’m home, Pads!” Lupin calls, smiling tiredly. 

The warm look disappears immediately when he catches sight of Regulus.

“What are you doing here?” he asks, narrowing his hazel eyes at him, his tone icy. “Where’s your brother?” 

“Hello to you too, Lupin,” Regulus replies, rolling his eyes disdainfully. “Sirius has just gone off to speak to Potter. Thought you were off on one of your weird wolf mission things, anyway? Full moon last night, wasn’t it?” 

Up close, he can see that the man looks even more frail and exhausted than usual, dark shadows under his eyes, his scars standing out sharply against his pale skin. One of them looks concerningly fresh. 

“Yes - and I was,” Lupin mutters, looking thoroughly irritated that Regulus has figured out his ‘secret.’ As if he himself hadn’t as good as told him, back in the cave. “But I decided to come back a bit earlier, before reporting to Dumbledore - wanted to surprise Sirius. Not that it’s any of your business.” 

He pauses for a moment, frowning at Regulus in a slightly less hostile way now, as if he’d only just processed what he’d said. 

“Wait…did you just say he’s gone to speak to James?” Regulus nods. “Why?” God, he already looks alarmed. 

Regulus hesitates, biting his lip. He supposes there’s not much help for it - he’s going to have to find out eventually. 

He takes a deep breath.

“Sirius has gone to speak to Potter,” he says slowly, watching the other man’s face warily, “because I’ve just told him who the spy in the Order is.” 

Lupin blinks at him, looking stunned. Whatever he’d been expecting Regulus to say, it wasn’t that, apparently. 

“ What?” he exclaims. “How do you…who is it?” 

He closes his eyes for a moment, gathering himself. 

“I’m sorry, Lupin. But it’s Pettigrew.” 

The silence that greets this statement is overwhelming, deafening. Regulus watches as all the colour drains from the other man’s face. 

“Wormtail?” Lupin whispers, his face frozen, his lips barely moving. 

Regulus nods. Lupin stares at him, every bit as thunderstruck as Sirius had been.

“I…no…but…” 

He looks as though he’s desperately trying to come up with a counterargument, a reason why it can’t be true, why Regulus has to be lying. Regulus just looks steadily back at him. Lupin takes a slow, shaky breath. 

“How do you know?” he whispers finally. 

“Because I ran into him when the Dark Lord summoned me to Malfoy Manor last night,” he says quietly. “Pettigrew was meeting with him. He was just leaving when I arrived - apparently he had ‘another meeting’ to get to.” 

Lupin’s eyes widen, staring at him in horror. 

“He hasn’t been working late, then,” the other man says slowly. 

“Evidently not,” Regulus agrees. 

Lupin lets out a hollow, shaky laugh. He sinks slowly down into the closest armchair, burying his face in his hands. 

Regulus fidgets a little, not sure how to respond to this - at least Sirius’s accusations had given him something solid to react to. Just as he had done on the night of the cave, he feels out of place, unwelcome, as though he’s intruding on a private grief that the other man doesn’t want him to witness. 

“I’m sorry, Remus,” he says awkwardly. 

It seems to take Lupin an age to lift his head from his hands and meet Regulus’s eyes again. Shock is written across his face, of course; but Regulus can’t help but notice that he also looks much more hurt than Sirius had been at the revelation. He swallows, and Regulus sees that there are tears welling in the man’s eyes. He looks away, awkwardly, not wanting him to know that he’s seen.

“If someone had asked me who I thought the spy was,” he croaks. “Out of everyone, I would never have said it was Pete. Not in a thousand years. But do you know what the worst part is?” Lupin looks up at him. “It makes sense, Regulus. It makes sense.” 

He lets out another tiny, incredulous laugh. Regulus has never heard a less amused sound. Lupin raises a shaking hand to wipe his eyes, and Regulus stands there, wishing he knew what to say. 

“So,” Lupin says, taking another shaky breath, clearly trying to steady himself. “Sirius is telling James? Right now?”

Regulus nods. “Yeah.”

The other man’s laugh is darker this time.

“I bet that’s going down well.” 

Regulus doesn’t know what to say to that.

After a moment, Lupin takes another deep breath, stands up and begins to pace aimlessly, just as he had done the other night. This time, though, Regulus doesn’t find it nearly as irritating - it’s comforting, in a strange way, to have some company while he waits for Sirius. At least Lupin isn’t throwing him a cold glare every two seconds, this time. 

Without really meaning to, Regulus begins to pace with him, falling into step with the other man. Neither of them say anything. They don’t need to, Regulus feels. They just need to know, both of them, that they’re not alone. 

Finally, after what feels like hours - but might have been minutes, for all he knows - there’s another loud crack , and Sirius is standing in the middle of the living room, looking even more haggard and pale than he had been when he’d Disapparated. 

“Sirius,” Lupin whispers, his voice hoarse with unshed tears. 

He closes the distance between them in two strides, pulling Sirius towards him and bending a little to bury his face in his neck.

Sirius tenses, but hesitantly wraps his arms around him in turn.

“Thought you were on your mission?”

“Came back early,” Lupin mumbles into his neck. “Wanted to surprise you.” 

Sirius’s face softens a little at that. He smiles slightly, despite himself, pressing a small kiss to the top of his head. 

“Did Reg tell you?” he asks quietly, his face settling back into an expression of exhaustion as he nods over at Regulus. 

“Yeah,” Lupin whispers. He squeezes Sirius a little tighter, looking up at him with wide, fearful eyes. “What did Prongs say?” 

Sirius shrugs a little, grimacing. 

“What do you think?” he replies bitterly. “It’s Prongs. He didn’t want to believe it - spent about half an hour trying to persuade me that I’m just being paranoid, that there has to be some kind of mistake. But eventually I got through to him - well, as much as anyone ever can get through to James I love everyone Potter. I told him that the spy is almost certainly somebody close to us.” He swallows, closing his eyes for a moment as though trying to work up the strength for what he has to say next. “So, no matter who it is…I suppose it’s still going to hurt like hell, isn’t it?” 

Lupin draws back, frowning at him.

“‘No matter who it is?’” he echoes. “What the hell is that supposed to mean?” 

Regulus looks down at his feet. He doesn’t want to see the pain dawning on Lupin’s face. 

“Well, anyway,” Sirius continues loudly, disentangling himself without meeting his boyfriend’s eyes, “Prongs and I are at least agreed that we can’t be certain - we need more proof. So we’ll go with Regulus’s idea.” 

“And what idea was that?” Lupin asks stiffly.

“We’ll tell Pete to come here,” Sirius answers. “And then we’ll confront him - all of us, Reg included - and see how he reacts. Give him a chance to speak for himself.”

The tense silence following these words seems to swirl and echo across the room.

“Sirius,” Lupin mutters, staring at him. “This is…”

“I know,” Sirius says quietly, still avoiding his eyes. “But we have to do this, Moony. We have to know for sure. Otherwise…” 

He trails off - but his meaning echoes loud and clear in the little room. 

With a small, helpless shrug, he turns away, walking to his bedroom and shutting the door without another word to either of them. 

The silence he leaves in his wake is almost unbearable. Regulus turns to look at Lupin - he looks somehow diminished, smaller than he’s ever seen him.

“Hey…Lupin…” he mutters awkwardly, without a clue what he’s even going to say. 

The other man takes a deep breath. 

“Back in a minute,” he announces, his tone overly cheery and casual, his voice cracked with unshed tears. “Bathroom.”

Lupin hurries out of the room before Regulus can say another word, leaving him alone. 

31st July, 1981

Regulus steps out of the fireplace into his brother’s living room again, his heart pounding violently in his chest. 

Lupin, he sees, is sitting quietly in his usual armchair near the fireplace, staring unseeingly into the flames. He barely even reacts to Regulus’s appearance, although he darts occasional glances at the two dark-haired men standing behind him.

James Potter has beaten him here, it appears - he and Sirius are standing with their heads bent together, muttering quietly to each other. Potter looks up at his arrival. 

If Regulus had thought the man looked anxious the last time he’d seen him, at the Order meeting at Potter Manor, it’s nothing to how he looks at the moment. He looks pale and clammy, his hazel eyes wide and fearful behind his glasses. He looks like a man who’s hopelessly lost, with no idea what to do with himself. 

“Regulus,” he greets him, with a brave attempt at a casual tone. 

“Potter,” Regulus responds, with an awkward nod, consciously trying to ignore the faint flickering in his stomach when the other man meets his eyes - a tiny remnant lingering from his teenage years. 

“Haven’t seen you for a while,” he says wryly, not really knowing how to converse in this moment.

“Side effect of having to go into hiding, I’m afraid,” Potter responds, with a grim smile that doesn’t reach his eyes. “Had to Disapparate under the trusty old Cloak.” 

He nods towards a shimmering, silvery grey cloak draped over the back of another armchair. Regulus glances at it, taken aback for a moment - he’d never realised Potter had his own Invisibility Cloak, along with every other privilege that the messy-haired man seems to possess. Although, thinking back to the myriad of times that he’d seemed to turn up in the unlikeliest of spots and wriggle his way out of detentions back at Hogwarts, he supposes it makes a lot of sense in hindsight. 

“Sorry for taking you away from Harry on his birthday, Prongs,” says Sirius, with a small sideways grin at his best friend.

James makes a valiant attempt to grin back at him.

“He’s not old enough to even realise it’s his birthday,” he replies, “and the poor kid’s seen so much of me over the past few weeks, he’s probably relieved to be shot of me for a bit. Besides, he’s so busy zooming around on that bloody broom you sent for him, Pads, I doubt he’s even noticed I’m gone yet.” 

“He likes it, then?” Sirius asks, his face brightening slightly. 

“Christ, he’s obsessed,” Potter answers, rolling his eyes theatrically - but Regulus can see the adoring pride in his eyes. “And you lot thought I was bad. We’ve already had to pack half the house away to stop him from crashing into things; Lils is probably gonna kill me when I get back, just for leaving her to deal with him by herself. But then, if anyone’s a match for that kid, it’s her.”

Despite Sirius’s answering grin, Regulus can tell that they’re both trying their best to keep the conversation light. They’re desperately trying to postpone the inevitable moment when they’ll have to face the painful truth of why they’re all gathered here. 

Sure enough, the forced smile drops from Potter’s face a moment later. He takes a slow, deep breath, looking more afraid and unsure than Regulus has ever seen him. 

“So…when is Pete due?” he asks quietly.

Sirius’s face tightens.

“About five minutes,” he answers, checking his watch. 

“What did you tell him?” Lupin asks, without looking around at the others. 

“‘Emergency Marauder meeting,’” Sirius replies, looking almost as pale and sick as Potter now. “He seemed a bit baffled, to be honest. Told him I’d explain everything when he gets here.” 

“And he has no idea that Regulus is here too?” James asks, nodding in his direction.

“Nope,” says Sirius heavily. “And given that Reg claims he bumped into Pete at Malfoy Manor the other night” - his mouth twists as he says it, and Potter sucks in a sharp breath as though he’s been punched in the stomach, despite the fact that he’s presumably already been told this - “we want to actually see whether it has any impact on him. Being caught unawares by Reg, I mean. Because if he does react badly, then…”

Sirius trails off. Regulus feels another hot, bitter surge of anger, burning in his throat - what extremes do they have to go to before his brother can just bloody believe him? 

But he bites his tongue, forcing it down - it can’t hurt to have solid proof, he supposes. Well, no, he amends, it can hurt; it might completely shatter the three men he’s standing with right now, in fact. But…at least Sirius will finally understand that he’s not lying. 

“Any minute now,” Sirius continues, his voice shaking slightly now as he checks his watch again. Potter looks at him with wide, desperate eyes, as if silently begging for more time to prepare himself. Sirius just shrugs at him helplessly. “Right, Reg,” he says, turning to him, “I don’t think he should see immediately that you’re here. Maybe if you just hide out in the kitchen for a few minutes, or in Moony’s little library, and we’ll think of some phrase to signal…”

“The Cloak,” says Lupin quietly.

“What?” Sirius and James ask simultaneously, both turning to frown at him. 

“He can just put Prongs’s Cloak on for a few minutes,” Lupin clarifies, barely raising his voice at all. 

He’s still staring into the fireplace as he speaks, without turning to look at either James or Sirius.

Regulus glances over at the silvery cloak draped over the armchair. Now there’s an idea. 

Sirius cocks his head a little, his eyes darting from the cloak to Potter.

“Would that be alright, Prongs?” 

Potter sighs. Clearly, he’s not especially thrilled by the idea - sometimes Regulus forgets that James Potter must harbour some resentment towards him , too, on Sirius’s behalf - but apparently lending him his precious cloak is the least of his concerns right now. 

“Yeah. Fine,” he says, running a hand anxiously through his already chaotic hair. “Go on and take it, Regulus.” 

Regulus nods awkwardly and reaches out to grab the Invisibility Cloak - it feels strange to the touch, like water somehow woven into silk. When he slips it over his head, it tumbles over him fluidly, effortlessly. Regulus glances down, stretches his arms out in front of him. It feels peculiar to watch as his own body vanishes completely from sight. 

He backs away from the others a little to give them space, standing near the wall so he has a clear view of the whole living room 

Sirius and Potter glance at each other briefly - James gives a tense nod, and the two of them sit down on the sofa next to Lupin’s armchair. 

All four of them lapse into silence, staring towards the fireplace. Regulus isn’t sure he’s ever felt so much tension in such a small space before - he can almost feel the other men’s hearts pounding, hear their thoughts racing. But none of them look at each other, none of them say a word - until the flames roar emerald green again.

Peter Pettigrew steps out onto the carpet, his small, watery eyes flickering over his three friends sitting waiting for him. 

“Sorry I’m a bit late, I was just -” 

He stops, frowning at their tense expressions, the way they’re sitting bolt upright in their seats as they stare at him. 

“What’s up?” he asks, with a nervous little laugh. “You guys look weird. Are you okay?” 

“We’re just fine, Wormy,” says Sirius quietly. He tilts his head a little, his eyes tracing over the shorter man’s face as though looking for something he’s missed. “Have a seat.” 

“Alright,” says Pettigrew, looking no less unnerved as he glances at Sirius, who has probably never focused his undivided attention on him before. Nevertheless, he sits down warily. 

“So?” he asks, turning his gaze to Potter now. “What’s this about an ‘emergency Marauder meeting’? You used to say that every time you’d thought of some new thing to leave in Filch’s office, or to lob into Snivellus’s cauldron. We’re not planning a prank on the rest of the Order now, are we?” 

“Not exactly, no,” says Lupin, clearly trying his best to sound casual. Pettigrew turns to look at him. “It’s a bit more complicated than that, actually, Pete - might take a while to explain. I can make you a cuppa, before we get into it?” 

“Um…okay. Sure,” Pettigrew replies, still looking bewildered. “Thanks, Moony.” 

Regulus sees a muscle clench slightly in Lupin’s jaw, but he nods, hoisting himself out of his armchair. Regulus notices that he’s limping a little as he walks over to their small kitchen - the full moon was only the night before last, he remembers. He’s clearly still recovering. 

Pettigrew’s watery eyes are lingering on Lupin too. Almost the moment that the scarred man vanishes into the kitchen and out of earshot, he leans in a little, towards Potter and Sirius. 

“It’s good to see Moony again, isn’t it? I was getting worried, I feel like I haven’t seen him for so long, with his wolf missions and everything. You said even you’ve been seeing a bit less of him recently, right, Padfoot?” 

Sirius’s fist tightens slightly on the arm of his chair, the knuckle whitening. Regulus is surprised at the surge of rage he feels, glaring silently at Pettigrew from the corner. 

“Well, there’s a war on, Pete,” Sirius replies quietly. “I suppose we’re all seeing a bit less of each other these days, aren’t we?” 

“Yeah. I s’pose,” Pettigrew replies, a flicker of disappointment crossing his face momentarily. Apparently giving up on Sirius, he turns to Potter. 

“How’s Harry, Prongs? How’s the new place?” 

James exchanges the briefest of looks with Sirius, before turning back to Peter, hitching a smile onto his face with what looks like enormous difficulty.

“Yeah, Harry’s great,” he answers, in a tone of forced cheerfulness. “Bit of a menace at the moment, though, Pads just sent him this toy broom and now we can’t pry him away from it…”

As James chatters on nervously, the strain in his voice becoming clearer with every word, Regulus sees that Sirius is still staring at Pettigrew, grey eyes narrowed as they flicker over his friend’s face. Pettigrew darts another baffled frown at him, opening his mouth - but he’s interrupted by Lupin’s re-entrance.

“Here you go, Pete,” he says stiffly, as he hands him a mug.

“Thanks, Moony, you’re the best,” Pettigrew responds, hastily grinning up at him as he takes it. 

Lupin just nods, his jaw clenched, anger and hurt flickering in his eyes. Regulus wonders, suddenly, if werewolves might have better hearing than the average person. 

“So,” says Pettigrew, sipping his tea as Lupin sits down next to Sirius. “Do I get to hear what this mysterious ‘emergency Marauder meeting’ is about, now? What is it that’s so ‘complicated’, eh?”

Sirius exchanges a brief look with Lupin, both of them pale-faced, looking a little sick. Then, Sirius turns and gives Regulus a deliberate nod. 

Taking his cue, Regulus swiftly pulls Potter’s Invisibility Cloak off and moves to stand behind his brother’s chair, directly opposite Pettigrew. 

Immediately, all the colour drains from the shorter man’s face, his suspicious frown replaced by a look of sheer horror. The mug slips from his grip, spilling dark tea all over the carpet, and he claps his hands to his mouth - but not before letting out a terrified squeak. 

Regulus looks quickly at his brother, who had sucked in a sharp breath at the sight of Pettigrew’s fear. Sirius closes his eyes for a second - when he opens them again, he looks somehow older than Regulus has ever seen him. 

“You seem a little nervous to see Regulus here, Peter,” says Lupin, with a kind of forced pleasant lightness in his tone, which seems strangely threatening. 

“I…of course I’m bloody nervous!” Pettigrew stammers, the terror plain in his voice. “What the hell is he doing here? He’s…he’s a Death Eater, Remus!”

Regulus feels fury beginning to bubble under his skin again; but Sirius speaks before he can say anything. 

“Well, you would certainly know a lot about that, according to my little brother here,” he says loudly.

A deafening silence echoes in the little living room in the wake of his words. Pettigrew’s gaze flickers over to Sirius, watery little eyes widening in fear. 

“What?” he asks. “What are you talking about, Padfoot?” 

He lets out a breathy, forced little laugh that makes the hairs on the back of Regulus’s neck stand up. Potter stares at his friend, an expression of utter heartbreak on his face. 

“Regulus has turned spy for the Order,” Sirius snarls, reminding Regulus suddenly of a dog intent on the scent of its prey. “ We might have been stupid enough to swallow your stories about ‘working late’, Wormy, but it seems you’ve had other commitments. Funny…Regulus says he could have sworn he saw you two nights ago, at Malfoy Manor, having a nice little chat with Voldemort…”

Pettigrew, predictably, flinches violently at the sound of the name. 

“Don’t know what you…” he stammers. “I’ve never …I wouldn’t…the Dark Lord…must be insane…”

His muttering is incoherent, desperate. Regulus notices that he’s not actually looking at Sirius any more; although he’s frozen to the spot, his eyes are darting frantically all over the flat, as though searching for an escape route. 

“Oh, I see,” Sirius replies, his voice dripping with sarcasm as he narrows his stormy grey eyes. “So Regulus just imagined you, did he, Wormy? Or do you have an identical twin that you’ve been hiding for ten years?” 

Pettigrew flushes blotchily. 

“I…no…I didn’t,” he mutters feverishly, still avoiding Sirius’s gaze as the other man glares at him. “That is…I don’t know what he thinks he saw, but…” 

“You know, Peter,” Lupin pipes up, “for someone who managed to have us all fooled, even Dumbledore - you’re a surprisingly bad liar.” 

Pettigrew turns to look at him, as does Regulus. There’s a cold fury in Lupin’s expression - but there’s pain underneath it, clearly etched into his face. 

“But I’m not lying, Moony!” he squeaks desperately. “I’m not! He’s the liar!” He points at Regulus with a trembling hand. “Why are you all suddenly trusting the word of a Death Eater over mine?” 

“I barely know you, Pettigrew,” Regulus says scornfully. “Until I saw you at Malfoy Manor the other day, I hadn’t even thought about you for years. If I was going to lie about somebody, why the hell would I lie about you ?” 

“Perhaps because you have been sent by the Dark Lord to spy on us ?” Pettigrew spits, glaring at him viciously. “Perhaps you have simply been sent to spread rumours, to sow discord among friends!” 

Regulus freezes at that, his blood running cold for a moment. Isn’t that almost exactly what Sirius had accused him of the other night? Is it possible that he’s got this far, only for Pettigrew to turn the tables on him now, at the last moment? Is he about to lose his brother for good? 

Frantically, he turns to Sirius, ready to defend himself until he’s blue in the mouth if he has to - but his brother’s gaze is still fixed on Pettigrew, fury twisting his face. 

“That’s all very well, Wormy,” he growls. “But, if that were true, how do you explain the fact that you nearly jumped out of your skin the moment you saw him? How could you have known he was a spy? You seemed pretty bloody terrified, considering nobody had even accused you of anything yet.” 

Pettigrew freezes, staring at Sirius. 

“Wh..what?” he stammers. “No…Sirius…I wasn’t …” 

Suddenly, the solution hits Regulus. It’s so simple, so obvious…

“Just tell him to show you his arm,” he says quietly. 

“His…what?” Sirius asks, looking at him in bewilderment. 

“Ask him to show you his left forearm,” Regulus clarifies. 

“But…why?” Potter asks, looking just as puzzled as Sirius and Lupin. “What does his arm have to do with anything?” 

Regulus hears the breath hitch in Pettigrew’s throat. When he turns to look at him, he sees that his face has drained of the little colour it had left. 

“Because everybody who joins the Death Eaters is branded with the Dark Mark on their left forearm,” he explains, determinedly avoiding his brother’s eye. “That’s how he calls us to him. Handy little tell, if you actually know what to look for. Of course, if I am lying about your little friend here, then there’ll be nothing to see.” 

“So…the other day…that’s how you knew to…?” Sirius whispers, looking horrified as understanding dawns across his face. 

Regulus nods stiffly. With an almost overwhelming surge of self-loathing, he rolls up his sleeve, extending his left forearm for the three of them to see, still not meeting Sirius’s eyes. 

It’s one thing to see the Mark on himself, but showing it to the others now - he feels like he’s bearing the ugliest, most repulsive part of himself, the darkest part of his soul, the part of him that doesn’t deserve forgiveness. He senses Potter, Lupin and Sirius all recoiling from him - although Potter at least tries to cover his disgust - and he hastily pulls his sleeve down again, feeling cold and sick. 

At least Fabian isn’t here, he finds himself thinking suddenly. 

Sirius inhales shakily, turning away from Regulus and turning his glare on Pettigrew instead. 

“Well, Wormy?” he demands, his voice far too loud for the small room, so that Pettigrew winces. 

Regulus recognises this ‘tactic’; the more unstable his brother feels, the less control he has over his emotions, the more he raises his voice. That was why he’d always ended up in shouting matches with their parents, no matter how many times Regulus had begged him to keep his temper, keep his head down.

“I…” Pettigrew is still looking desperately around the room, as though trying to find a hiding spot. “I am not going to show you my arm, Sirius!” he squeaks. 

“Why not?” Lupin asks. In contrast with Sirius, his voice is quiet, cold; Regulus is reminded of the way he’d spoken to him , back in the cave. Pettigrew, for his part, looks even more frightened by Lupin’s calm, quiet voice than by Sirius’s shouting. “If there’s nothing to see, Peter, then what harm could there be in us looking? Just humour us for a moment.” 

“There isn’t anything to see,” Pettigrew insists, though his voice is high-pitched, eyes wide with terror. “But regardless, I am not going to show you my arm, because…because…” Regulus can almost hear him sifting desperately through his brain for a reason. “It’s private, I’m not as bloody confident as you lot, I never have been -” 

“Please, Pete,” says Potter suddenly, finally speaking up. Everyone turns to look at him. “No more lies. Enough.” 

Unlike Sirius, whose voice is full of barely controlled fury, he sounds tired and very, very sad. 

For a moment, everyone falls completely silent, watching James and Peter stare at each other. There’s nothing vicious or angry in Potter’s expression at all. As he looks at his oldest friend, the one who had been part of his life even before they’d started at Hogwarts together, he looks almost pleading. 

Pettigrew turns, if possible, paler still as he looks back at him, the man who had been his protector and his champion since they were children. 

Finally, he swallows and gives one shaky nod. It’s as though, even now, some part of him instinctively has to obey James Potter. He looks away from the bespectacled man’s face, as though it’s too much for him, and, very slowly, rolls up his left sleeve. 

There it is, jet black against his pasty skin - a Dark Mark, identical to the one on Regulus’s arm. For a moment, time seems frozen in the little living room, everybody staring at it. 

Regulus can practically feel the Marauders’ childhood, their vision of themselves as the golden heroes of their story, crashing down around them. 

Potter breaks the silence first.

“Why, Pete?” he asks quietly, his voice cracked with heartbreak, searching his old friend’s face as though seeing him clearly for the very first time. “Why would you do this? We all love you, we all would have done anything to protect you. You know that.” 

Suddenly, Pettigrew’s face contorts. He lets out a shriek of desperate, humourless laughter. 

“ You would have protected me?” he exclaims, incredulous. “You haven’t been strong enough to protect me since we were fifteen, James! We’re not kids mucking around at Hogwarts any more, we’re at war - and the Order is losing ! I know it, you know it, we all know it!” 

James stares at him, evidently lost for words.

“It’s time you three heroes grew up and faced facts,” Pettigrew continues, voice dripping with scorn, face still twisted in that ugly, bitter expression. It seems that now he’s started, he can’t stop, all of the resentment he’s kept bottled inside him for years finally spilling out. “The Dark Lord is gaining power everywhere - what is there to be gained, any more, by resisting him?” 

“What is there to be gained?” Sirius echoes indignantly, fury etched across his face. 

Pettigrew turns his gaze on him - and suddenly there’s such a look of venomous hatred on his face that Sirius goes silent, flinching back as though he’s been burned, his rage replaced momentarily with a look of shock. 

“And as for ‘we all love you,’ ” he continues, breathing heavily, “don’t give me that shit.” He raises a shaking hand to point at Sirius. “ He thinks I’m nothing, insignificant, weak - he’s treated me like a joke since we were eleven years old!” 

“You are insignificant and weak,” Sirius snarls back at him, apparently recovering from his shock. Potter looks sideways at him, more uneasy than ever. “That’s why, before Reg came to me, I was about to suggest to Prongs that he should make you his Secret Keeper.” 

Pettigrew’s glare lessens slightly, apparently taken aback by this revelation. 

“ I’m a bit too obvious a choice, you see,” Sirius explains. “But you, Wormy,” he continues, malice flickering in his grey eyes now, “ you are such an insignificant, unimportant, cowardly little rodent, I was convinced that Voldemort would never in a million years think that James would have chosen you. The perfect double bluff, I thought. Believe me, I certainly wasn’t thinking of any prodigious magical skill - or any talent to speak of at all, really,” he finishes cruelly, with a harsh bark of laughter. 

The room falls silent again in the wake of this outburst. But then, to Regulus’s surprise, a slow and self-satisfied smirk begins to creep across Pettigrew’s face.

“But I can’t be all that untalented, can I?” he breathes. “After all - I’ve had the whole lot of you fooled for months now, haven’t I? You never noticed what was right under your nose, Sirius - clever and talented as you might be, it was so easy to make you look the wrong way. Much easier than I thought it would be, in fact. Of course, his furry little problem has been quite convenient, not to mention all those missions Dumbledore’s been sending him off on - but really, all I had to do was drop a few hints here and there, a few doubts. After all, we’ve all been so worried about you, Moony…”

Lupin and Sirius both turn deathly pale at this, as Pettigrew grins vindictively, baring his teeth. Sirius looks sideways at his boyfriend, shock and guilt mingled in his expression.

“So,” Pettigrew whispers, his voice full of quiet venom again as he looks at Sirius. “Perhaps I’m not quite so weak and insignificant as you thought, Padfoot. Or perhaps the Dark Lord is right. Perhaps I was just able to toy with you, like James used to play with his little Snitch, because I could see so clearly how love was making you weak.” 

Without warning, Sirius whips out his wand, his face contorted in a snarl as he makes a furious move towards the shorter man - but Lupin throws out an arm, holding him back with a warning look. 

“The McKinnons are dead because of you,” Lupin says quietly, turning back to Pettigrew, staring at him as though he still can’t quite believe any of this is real. “Edgar Bones…Benjy Fenwick…Dorcas…Gideon…”

“Yep,” Pettigrew replies bluntly. “It’s regrettable, of course - but this is war. These things happen.” 

“And if Sirius had made you the Potters’ Secret Keeper,” Lupin continues, “would you really have sold James and Lily to Voldemort, too? Would you have hurt Harry?”

Pettigrew’s gaze turns to Potter, giving him a cold, clear, calculating look. 

“Look,” he says quietly, with a little shrug, his voice almost apologetic now. “I’m not saying I would have been proud of it. It certainly wouldn’t have been anything personal, Prongs -”

“Don’t call me Prongs,” Potter says quietly. “You don’t get to say that any more, Pete.” 

Something that could almost be called regret seems to flicker across his face for a split second - but then Pettigrew shrugs again. 

“Fine - James, then,” he says, as though it makes little difference. “You’ve always been kind to me, and I’m grateful for that - I really am. But surely even you, in your noble heroism, must understand that anybody who continues to stand against the Dark Lord runs a very high risk of ending up dead. And personally, I’m not prepared to take that risk. I have absolutely no intention of ending up on the losing side of this war. So…” he gives another little shrug. “I suppose I would have done whatever needed to be done.” 

James stands stock still, gazing at him with an expression of utter horror on his face. Even Regulus, who has witnessed more than enough selfish sociopathy for a lifetime, finds himself shocked, nauseated. 

Sirius and Lupin, on the other hand, are not staring at Pettigrew; they’re looking at each other. A silent understanding seems to pass between them.

“Together?” Sirius murmurs. 

Lupin gives him a tiny, almost imperceptible nod. 

“Yes, I think so,” he replies calmly. 

“Wh..what?” Pettigrew stammers. 

The smirk has suddenly vanished from his face; he looks from Sirius to Lupin and back again with an expression of unease. 

Before Regulus can process what’s happening, both men have their wands raised, pointing directly at Pettigrew’s chest. He freezes, the nervousness in his pointed face turning immediately to terror. 

“Given how desperate you are to save your own skin, you probably should have thought this through a bit better, shouldn’t you, Wormy?” Sirius says, his voice twisted with rage. Regulus can’t help but shiver slightly - he’s never seen his brother look so menacing. “You should have realised; if Voldemort didn’t kill you, we would.” 

“Goodbye, Peter,” says Lupin simply, his voice strangely chilling in its calmness.

Christ, Regulus thinks, stunned, as Pettigrew flinches back, instinctively raising his hands to cover his face…

“NO!” 

Regulus jumps at the sudden shout. 

Without warning, Potter flings himself in front of Pettigrew, shielding him with both arms out, facing Sirius and Lupin. Pettigrew blinks, looking just as shocked as everyone else. 

“What the fuck are you doing, Prongs?” Sirius demands, glaring at his best friend as he recovers. “Get the hell out of the way!” 

“No I bloody won’t,” James replies, breathing heavily as he looks back at Sirius, raising his own wand as Pettigrew cringes behind him. 

Regulus had always thought Potter mild-mannered, annoyingly so - unless Snape happened to be involved, of course. He’s certainly never seen that expression on his face before. 

“You can’t kill him,” Potter continues. “I won’t let you, you hear me?” 

“But…” says Lupin, blinking at him. “But… James…” 

“But you heard him, Prongs!” Sirius protests, jaw clenched as he stares at him in furious disbelief. “That piece of filth would have handed you over to Voldemort - you, Lily, even Harry - without turning a hair! His own pathetic skin means more to him than your whole family, he just bloody admitted it! And he was going to try and blame Moony for all of it, too!” 

“I know that, thanks, Sirius,” Potter replies, his face pale, blinking rapidly as though trying to force himself not to cry. “But you can’t kill him. Even if he doesn’t care about me any more… I still care about him. Besides, if you two killed him…you’d just be sinking down to his level, wouldn’t you? 

“But -”

“I won’t have my best friends in the world become murderers,” James says loudly, cutting Sirius off, “just for him. Look, I’m sorry - I love you both. You know I do. But I warn you now, if you kill him, in cold blood - I don’t think I could let either of you hold Harry, ever again. I couldn’t even let you near him.” 

Regulus watches as the two of them stare at Potter, frozen to the spot and breathing heavily as they process his words, their wands still raised. 

“I’m never going to be able to forgive him,” James says quietly, his voice breaking. “ Please don’t make a choice that means I can’t forgive you , either.” 

Sirius and Lupin turn to look at each other silently for a moment, both deathly pale. The moment seems to stretch on endlessly, an eternity held in a second. 

Then, finally, the two of them reluctantly lower their wands, in unison. 

Potter breaths a sigh of relief, relaxing his protective stance and lowering his arms. Pettigrew, who had been crouched behind him with his hands over his head, looks up in disbelief, as though he can’t believe his luck. 

“What do you suggest we do with him then, Potter?” Regulus asks quietly.

James turns around to look at the short man, grief etched across his face. 

“I suppose we’ll have to take him to Dumbledore, won’t we?” he says. “We’ll explain everything to him, he’ll know what to do, he always does. Peter might…” he swallows, his voice cracked with tears. “Peter might have to be handed over to the Ministry for trial.” 

“You really think that’s safe, Prongs?” Sirius asks sceptically. “You think we’ll be able to contain him? How do we stop the little rat running straight back to Voldemort?” 

“He…he won’t,” Potter responds, though his voice is full of doubt. “He won’t do that - not now he knows that we know.” 

But he hesitates, looking down at his oldest friend again. Pettigrew, realising that the immediate danger has passed, is looking up at them with a shrewd, calculating expression on his face. 

“Look, Pete,” James says quietly, crouching down so he’s at eye level with him. “I want to help you, really I do. But I need you to remember that Regulus is in the Order now. So, if you try to go back to Him , you need to understand that we’ll hear about it pretty quickly, and -”

But he never gets to finish the sentence - because suddenly, there’s a deafening bang , accompanied by a vivid blast of red light. Potter, who had been crouching so close to Pettigrew, is thrown violently across the room, banging his head, hard, on the opposite wall. 

Regulus, Sirius and Lupin all jump, crying out in shock and raising their wands, disoriented and confused. Before Regulus can process what’s happening, his wand is flying out of his hand, along with the others’, all three landing on the floor on the other side of the room with a clatter. 

A small crack , and Pettigrew has vanished. Still a little dazed, Regulus thinks for a moment that he must have Disapparated, but - 

“There!” Lupin cries, pointing. A large grey rat is sitting next to the open box of Floo powder next to the hearth. Still stunned, staring in disbelief, they watch as Pettigrew grabs some in his paws, throwing it into the fireplace. 

Sirius lets out a roar of rage, pelting towards him - but too late. The grey rat has taken a flying leap into the fireplace, long bald tail arcing through the air behind him - and vanished in a roar of emerald flames. 

“ COME BACK HERE, YOU BASTARD!” Sirius yells into the fireplace, grabbing his own handful of glittering powder. 

“There’s no point, Sirius,” Regulus says heavily. “He could be anywhere - that would have been why he transformed first, so we’d have no clue where he was going. Then again, I don’t know if you’re supposed to travel by Floo while in Animagus form, and I imagine he’s never tried it before, either. I suppose he might have just killed himself in the attempt - but I wouldn’t count on it.” 

Sirius swears loudly, his fists clenched as he glares into the fireplace, the emerald flames dying down now. 

“Sirius,” Lupin whispers, his face pale and anxious as he tugs on his sleeve. “Sirius… Prongs…”

Sirius whips around to look at his best friend. Potter is lying prone on the floor where he had banged his head, a dark trickle of blood making its way down his forehead. Regulus watches as his brother’s eyes widen in fear. Together, Sirius and Lupin hurry over to him, Regulus at their heels. 

“Prongs?” Sirius asks desperately, crouching next to him. “Prongs? You okay? Wake up !” 

His voice breaks - it sounds like he’s pleading, begging. Regulus has to look away for a moment - it reminds him too much of the night when Sirius had been hurt.

 “ Prongs!” Sirius is shouting at him now, shaking his shoulder none too gently. “Dammit, wake up, you bastard!” 

“Not very nice thing to say,” James croaks weakly, his eyelids fluttering halfway open. “‘Specially not to a wounded hero.” 

“Oh my god,” says Sirius, his own voice weak with relief. Lupin inhales shakily next to him. “How’re you… are you okay?” 

“Been better,” Potter mumbles, his eyes sinking shut again. “But…yeah, Pads. Think so. M’okay.” 

“Christ ,” Sirius mutters, sitting down on the floor next to him. Next moment, he’s sitting with his head on his knees, sobbing in great, heaving gasps.

Regulus stares at him in shock. So does Lupin.

“Sirius…” Reg stammers. “What the…?”

“I was…I really was going to tell you that you should make him Secret Keeper, Prongs!” Sirius exclaims between sobs. “You…you could have died …you, and Lils, and Harry…and it would have been my fault, all mine! And…and I’ve been treating Moony like shit for ages, too - because I completely fell for that bastard’s crap, even though I should have known better, I know I should! God, I’m such an idiot…” He raises his head to look at his boyfriend, his face streaked with tears, his eyes wide and apologetic. “I don’t even deserve you, Moony,” he whispers. “But I love you, so much. God, I’m so sorry …” 

Regulus sees the look of immense relief on Lupin’s face, as he kneels next to Sirius. 

“You are an idiot, yeah,” he murmurs. Sirius half-laughs through a sob. “A complete idiot. But I love you too. Even so.” 

He reaches up to brush a tear away with his thumb. Sirius’s sobs start anew, his body shaking, and Lupin wraps both arms around him, rocking him slightly. 

“Shh,” he whispers. “It’s okay, Pads…we’re okay now…”

“It is not okay!” Sirius exclaims against his chest. “It’s not! And…Regulus…I’ve been such a dick to my brother, too…”

“Yeah, well…nothing new there, then,” Regulus says awkwardly, trying to make him laugh. 

Unsurprisingly, it doesn’t work - but Sirius looks up at him, his eyes red-rimmed, his gaze completely earnest and open. 

“ Thank you, Reg,” Sirius gasps. “Thank you, thank you -”

“Alright, I get it!” Regulus interrupts. 

Despite everything that’s happened tonight, he can feel a grin spreading across his face. Somewhere deep inside him, something warm seems to click back into place, mending itself. Or perhaps just on the way to mending - but that’s good enough, for now. 

“You’re welcome, you prick,” he continues, rolling his eyes dramatically. “I can see why you need me around, that’s for sure.”

Sirius breaks into a storm of fresh sobbing, and Lupin wraps his arms around him more tightly, murmuring soothingly into his hair. 

Regulus shakes his head, still grinning a little as he turns back to Potter. 

“Are you actually alright, Potter?” he asks him quietly. “Or did you just say that to make my stupid brother feel better?” 

James grins faintly without opening his eyes.

“Not just for stupid brother,” he mumbles. “And…think so. Not great. But…m’okay. Just…tired. Sad, I s’pose.” 

He isn’t sure what to say to that. The pain is clear in Potter’s voice, despite the fact that he sounds half-asleep. The blood trickling down under his glasses is standing out vividly against his skin, much paler than usual. 

Regulus tuts loudly to cover his concern.

“Well, we can’t just leave you like this, can we?” he asks. “How many fingers am I holding up, Potter?”

James grins dopily, eyes still closed. 

“One, and you can put it down, because that’s rude , Sirius.”

“For god’s sake, I’m Regulus .”

“Yeah…thass what I meant,” Potter slurs. 

“Open your eyes,” Regulus sighs. James cracks them open halfway. “How many fingers?” 

“Four,” he murmurs.

“Close. Three. Think you have a concussion.” 

He turns to Lupin, knowing his brother won’t know anything useful. 

“Lupin, you got a healing kit or something here? Murtlap essence?” 

“Yeah, somewhere in the bathroom,” Lupin calls back, still holding Sirius as he sobs. “You can just Accio it.” 

Regulus mutters a Summoning charm, and the kit comes soaring towards him. 

“This might sting a bit, Potter,” he warns him, as he dabs some Murtlap essence onto a wad of cotton.

“Think ‘m used to things stinging, by now,” Potter mumbles back, but he still winces as Regulus presses it against his wound.

“Told you,” Regulus mutters, rolling his eyes. 

“Sirius is right, y’know,” James says, opening his hazel eyes, suddenly sounding a bit more awake. “Siriusly, Regulus…thank you. We’d…be… screwed, without you.”

“Yeah. I know,” Regulus replies, with a small grin. As it turns out, talking to Potter is much more straightforward than talking to Sirius. “You idiots are welcome.” 

Potter nods, subsiding into silence as his eyes drift over to the other two, apparently thinking. It looks like hard work. 

“So,” he says suddenly, making a valiant attempt to sit up, as his eyes focus on Regulus again. “How’d you like to be our new Secret Keeper, Reg?” 

END OF PART ONE