No Greater Sin

Harry Potter - J. K. Rowling
M/M
Other
G
No Greater Sin
Summary
Regulus has always known he's destined to drown. He feels it somewhere deep in his chest, past his rib cage, nestled behind his organs. He feels it in his arm when his mother squeezes it a little harder than a mother should. He felt it, the water rising in his throat, when his brother slipped out the window and into the night. He often wonders if it'd be easier to just let himself sink.He often wonders if he has a choice.---Regulus gets sent back to school with a mission from the Dark Lord himself— find the “beast in the chamber” and claim its fangs without killing it. But when a certain curly-haired bespectacled boy asks for a rather large favor, everything suddenly gets a lot more complicated.
All Chapters Forward

Dumbledore's Office

Regulus takes his place by the window quietly. Pandora sits next to him after a second, and the others pile in behind her. 

He’s so tired. 

So desperately tired. 

Pandora nudges him gently. He lifts his head to look at her. “Hey,” She starts. “We’re going to school now.”

He nods at her, a little confused. She rolls her eyes, but smiles. “You’re leaving them behind, Regulus. So leave them behind.” Outside, the trees whip by. 

Pandora’s words crawl into his chest and warm it slightly. “Ok,” he whispers softly. 

“Hey Dora,” Barty jumps in. “did you know Reg was a-” Evan elbows him sharply, and Barty yelps, but lowers his voice to a whisper. “Parselmouth?”

Pandora glances between them. “You didn’t?”

“You told her, but not us?” Barty looks up at Regulus, betrayed. Regulus tries not to smile. 

“I didn’t tell her.”

Pandora leans back into the seat. “I thought it was rather obvious.”  

 

---

 

When James gets to the Come and Go room, he’s alone. Early; for the first time ever. He takes a seat on a couch, and waits. 

The trip back was easy enough. He and Sirius are talking, which helps. It’s still a little frosty, just a bit, but they ignore it. That’s the way it’s always been. 

James runs a hand through his hair. 

The door handle turns, and Regulus steps through. Despite his usually pale complexion, he looks sickly. There are dark circles under his eyes. He pauses on the threshold, staring at James, who stands up. 

“Hey Reg,” He starts. “How was your break?” He sees the answer in Regulus’ eyes, but he lets him lie. 

“...Fine.” Regulus takes a breath. “You?”

“It was good. It was… good. I saw dad.” Something catches in James’s mind. An inconsistency. “Are you using glamour right now?”

Regulus shuts his eyes, still not moving from the door. When he doesn’t say anything, James tries again. “Reg?”

Regulus takes a step in, and shuts the door. His skin flickers, and the disillusionment charm vanishes. There's a cut, long and deep and only barely scabbed over, high on his cheek. 

James forces himself to take deep breaths. When he looks at Regulus, he sees Sirius, and all the times he came back to school covered in bruises. All the times James couldn’t protect him. 

“What happened?” 

Regulus’s face is blank. “It doesn’t matter.” 

“But they didn’t- they didn’t find out about this? Us?” 

Regulus smiles at the ground, but it lacks humor. It’s more of a grimace. “No. We’re fine.”

James breathes a little sigh of relief. “Why haven’t you healed it? Do you want help?”

Regulus’s eyes glint. “You really think I couldn’t manage a healing spell by myself?” 

“I mean, last time…”

Potter.” 

James tips his head, holding up his hands in mock surrender. “Ok, you don’t need my help." He tips his head. "…But why haven’t you healed it?” 

Regulus looks up, holding James’s gaze. There’s conflict in his eyes, a little cloudy. The rest of his face is fully devoid of emotion, wiped clean. He seems to come to a decision.“I’m not allowed to.”

And. 

Ok.

James has to walk away. Fully turning and pacing the room, focusing on his breathing. “Okay,” he says on an exhale. “Okay. What do you mean you’re not allowed to?”

“I’m not allowed to heal myself. Not yet. She’ll know if I do.”

James clenches his fists, then unclenches them. Tries to calm himself down. “Why not?”

“I haven’t learned my lesson yet. That would be taking the easy way out.” There’s an eerie calm to Regulus’s voice; like still water, waiting for the rock to send ripples across its surface. Beyond feelings- beyond caring. 

James isn’t an angry person. Not really. But there's a cold sort of fury that slices through his veins and descends upon him when he’s faced with Walburga’s handiwork. When Sirius was on their couch, Effie frantically patching him up, James had to squeeze Sirius’s hand hard just to keep the anger down. It was all consuming; the need for her to repent, to hurt her as she hurt, to punish her. It burnt through him, leaving a scorched trail of his human decency behind. James hated how helpless he felt against her. The weakness made him more angry, and thus started the vicious cycle.

So, no. James isn’t an angry person. Unless it comes to Walburga Black and Orion Black.

“Reg, you should be allowed to heal your wounds.” 

“How’s your father? Did the potion have any effect? I imagine-”

“Regulus.”

“-it wouldn’t, because it’ll need time to set into the muscle. How’d you get him to agree?”

James rubs a pained hand across his forehead. Maybe, just maybe, this was Regulus’s way of telling James what he needed. Letting him know how he can help. He needs a distraction. James can do that much. So… “He’s ok. Weak. He took the potion to make me happy, I guess. It didn’t have any effect yet.”

Regulus nods. “We’ll work on it.” A pause. “There’s something I’ve been meaning to ask you.”

“Yeah?”

“How did you know to come to me? I mean, in the first place? How did you know I was… apt at potions?”

James shrugs. “Lily.”

He can’t interpret the look that flashes across Regulus' face. His eyebrows draw together. “How did she know?”

“She went to a Slug Club dinner, and you were there. Apparently Slughorn told her she was his second best student. When she asked who was his first, he told her it was you.”

Regulus frowns. “I remember that, vaguely. She looked upset.”

James laughs, picturing her irritated expression when she’d come back to the common room that night. It was, admittedly, very cute. “Yeah. She was not happy. She worked hard for that spot, you know. Potions is her favorite subject.” He smiles. “I guess you two have that in common.”

“Potions is not my favorite subject.” Regulus says quietly. 

“Oh?”

“History.”

James rolls his eyes. “I should’ve known. That would make Lily even madder, you know.”

Regulus crosses his arms. “How so?”

“You’re the best in a subject that’s not even your favorite. You don’t enjoy it as much as she does- yet you're still better.”

“Enjoying a subject doesn’t make you good at it.”

“Ah, but it helps. And she loves potions. She’s top in our class in everything, potions included, but your top in the school. That’s why I found you.”

“Right.” Regulus stares at him then blinks, and looks back at the table. “I had some ideas over break. For the next stage, provided this one works.” He starts to sort ingredients. 

James watches him for a moment, then moves to help him. They talk comfortably, all past conversations forgotten. It’s quiet, gentle. Easy. 

And when Regulus’s shaking hands knock over a few vials, James pretends not to notice. 

 

---

 

Regulus is furious. At Slughorn, specifically. When he’d asked to transfer out of Astronomy, Slughorn simply moved him to the next level up. That was not at all what he wanted. 

But here he is, standing in the doorway of a classroom, staring at a bunch of sixth years. He gives them his best slightly distasteful expression. 

Professor Sinistra glides over to him. “Mr. Black. Welcome. It’s an honor to have you in my class, I’ve heard great things.” She looks him up and down. “With your legacy, I expect great things.” 

After glancing around the classroom, she points him to an empty seat. “There, take that one, Mr. Black. Next to Mr. Lupin there. Just for now, while we’re still in the classroom. Though I suppose once we move to the astronomy tower you’ll share a telescope too.”

Regulus considers cursing her, cursing Lupin, then walking out. Maybe finding Slughorn and cursing him too. He takes his seat instead, not looking at the boy next to him.

He hears Lupin chuckle. “This is going to be fun,” he mutters. Regulus ignores him. 

Professor Sinistra turned her silver eyes on him. “Mr. Black, are you completely caught up on the 5th year syllabus and ready to progress with the rest of the 6th years?” 

“Yes, Professor.” And the 6th year syllabus, and the 7th…

“Perfect. I believe today we are reviewing constellations.” 

It takes effort to not bang his head on the desk. Lupin smirks. “Why are you here? Even Sirius tested out last year, but McGonagal let him drop the subject entirely.” 

“Slughorn seems to have misunderstood my request,” Regulus mutters. “That or he doesn’t understand the Nobel House of Black very well.”

“In his defense, few do.” 

Regulus opts to stay silent. 

Sinistra writes something on the board.“Does anyone know the Cetus constellation?” 

Regulus refuses to raise his hand, just on principle. Sinistra locks her eyes on him, but luckily somebody else answers before he has to. 

“How was your break?” Lupin whispers. Regulus wishes people would stop asking that. 

“We don’t have to do this.”

“Do what?”

“Talk.”

“Oh, thank God.”

They go silent as Sinistra reads out some very simple instructions, making sure to explain each one carefully. In Regulus’s peripheral, Lupin tips his head slightly. “But you should know, Sirius is starting to get suspicious.”

That makes Regulus involuntarily jerk a bit. “About?”

“Whatever you do on the second floor late at night.” Lupin pauses as Sinistra drifts by their table handing out worksheets. “I have my own hypotheses about that, though I haven’t shared them with him.”

Regulus grits his teeth, attempting to focus on his paper. “Why’s that?”

“I’ve still got that pesky little curse on me.” 

Regulus had forgotten about that. Once again he thanks his past self. “So, you’ve told them the rest then?”

“What?”

Regulus waits a beat when Sinistra looks over at them. He leans over slightly, so he can whisper. “Earlier, your reason would’ve been simple blackmail. Now, when I ask why you haven’t told them, your first instinct is the curse. Which means the issue is no longer about the content of the information but instead the method of relaying it.” 

“Sirius mentioned you were smart.”

“I don’t care what Sirius says. What are your hypotheses?”

“Something about what happened in the library, you know- with the book.” He would say the word Basilisk, Regulus knows, but the curse prevents him. 

“Right.” 

They go quiet, and Regulus starts thinking. He’d need to be more careful, especially with Lupin so close to the truth. He knows- or will, soon. Regulus can feel the Dark Lord’s eyes on him. He doesn’t have time to be so reckless. What would his mother say? Honestly- what would his mother do

He’ll need to switch up his schedule, rearrange it a bit, but that’s doable. Everything’s still under control. He tries to take a deep breath, but it shakes a bit on the exhale.  

He can feel Lupin’s gaze on him, but he ignores it, staring straight ahead. He pushes the worksheet away from him.

He finished five minutes ago.

 

---

 

Regulus sits on Slytherin’s bed, leafing through the journal. The Basilisk lays in its sleep chamber, head resting on the floor of Slytherin’s room through the door. 

Mostly it’s a diary, Slytherins day-to-day routine. Sort of boring, but sort of fascinating, really. 

The Basilisk hisses softly. Anything of interest?

Everything. Regulus flips another page. I won’t be able to come tomorrow. 

Why not?

Dumbledore has asked to meet with me. Again. 

My boy did not like Dumbledore. 

Regulus looks up at her then. Your boy… the one who did that to you? He nods to the scar on the Basilisk’s cheek. What did you call him? 

Tom Riddle.

Regulus nods. He touches his own cheek faintly, runs his hand over the cut there. They match now. I might have to agree with him , he says. I’m not too fond of Dumbledore myself. 

What does he want?

For me to be a spy. To work with him, feed him my family's secrets. The Dark Lord’s secrets. 

The Basilisk flicks her forked tongue. You are loyal to your Lord. 

I- yes. The words feel dirty, somehow. Disgusting. They taste like guilt, but Regulus spits them out anyway. I am. I have to be. 

What secrets does he want? 

The Dark Lord’s plans. 

The snake lifts her head slightly. What are those? 

Regulus stares at the Basilisk, a surge of sharp pain tearing through his chest. Twisting in his gut. I don’t know. 

Would Dumbledore hurt you? 

No. 

The snake moves its head in what might be a nod. Would your Dark Lord hurt you? 

Regulus touches his cheek again, feels the raised skin, the sting of pain. Yes . He lets his hand drop. But I am loyal.  

Out of fear.

Regulus puts down the journal . Out of respect, and intelligence. 

He hurts you. 

Only-

Your face. Your body. He hurts you. 

Regulus shakes his head quickly, his hands starting to tremble again. Only when she needs to. 

There’s silence for a moment, and Regulus realizes what he’s said.

He stands up quickly, brushing off his clothes. There’s dust everywhere the room, and it clings to its inhabitants the second they enter. He picks up the journal, walking to the desk to put it down. I have to go. 

No, you don’t. 

I want to go, then. 

The Basilisk lifts her head. To see your sun? 

I have no sun. 

Like my master- like Gryffindor. You have a sun. 

Regulus needs to get out of here. He puts the book in the drawer and shuts it quickly, turning around. He walks out of the room, down the tunnel. Through the chamber, matching his breaths with his steps. He can hear the Basilisk following, waiting to be granted sight. 

He pauses at the door, turning to look at it, raising his wand. And for the first time, the Basilisk ducks its head, looking away. Regulus draws a sharp intake of breath.

She’s shielding him. When he casts the counter curse, the Basilisk won’t be looking at him. He’ll be safe. She’s protecting him- and the weight of that realization hits Regulus in the stomach like a bludger. 

He shudders, and raises his wand. This is the test, he realizes. If he heals her and she doesn’t look at him, she no longer wishes to harm him. She trusts him. 

So this time, he stands tall. He doesn’t turn away, or shield his eyes. He stares at the back of the Basilisk’s neck, wand raised. “Oculus.”

He can tell the Basilisk's eyes heal, but she doesn’t turn around. He swallows. Thank you, he whispers. His throat feels tight. Slowly, he backs up, stepping through the door and closing it behind him. 

 

---

 

Dumbledore sets down a pot of tea in front of Regulus. “I’d like to apologize.”

Regulus stares at him. Dumbledore sets out two cups. “Intercepting your mail was the wrong way to approach that situation.” He reaches into the top drawer of the desk and pulls out the letter, handing it to Regulus. He takes it gingerly, keeping his eyes on Dumbledore. “Thank you.”

“Upon reflection I’ve also asked the house-elves to no longer watch the Slytherin common room.” Dumbledore’s gentle smile crinkles the corners of his eyes. He closes the drawer and then pours out the tea, pushing Regulus’s cup across the table to him.

“I would hope you can appreciate my reasons for doing so,” Dumbledore says, taking a sip. “In these times-”

“In what times?” Regulus cuts in, momentarily forgetting his manners. “You keep saying these times, but what do you mean? Because you never tell the students anything.” 

“Connection to Voldemort or no, you’re involved in your family’s business enough to know what times I’m referring to.” 

Regulus stays silent. 

“As I was saying, in these times it's crucial to be on edge, constantly vigilant. While intercepting a student's mail might not be the best way to go about that, I need to protect the greater good.” Something flashes across Dumbledore's face at those words. 

“Why did you choose my mail, then?” Regulus picks up his cup, letting the warmth seep into his fingers. He takes a sip and sits back a bit in his chair. “Why not anyone else in Slytherin?”

Dumbledore doesn’t blink. “To put it simply: the Noble and Most Ancient House of Black. It has a reputation. A few of your family members are known death eaters and currently sought after by the Ministry.”

Regulus, unfortunately, can’t fault that logic. “What about Beauxbatons? How do we know that won’t happen here?”

“I believe Voldemort has supporters here, among the students.” Dumbledore’s gaze cuts through Regulus. “I don’t believe he’d harm those that love him. Not if they are still of any use to him.” Dumbledore shakes his head. “But to discuss politics is not why I’ve called you here today. It’s as I said: I just wanted to apologize, Mr. Black. What I did was invasive and wrong.”

Regulus nods cautiously, taking a careful sip of his tea. He doesn’t trust his apology at all. There’s something very wrong about all of this- but he can’t put his finger on it. Is Dumbledore being genuine? Or is he just waiting for the right moment to strike?

“I do have just one question, Mr. Black.” Dumbledore folds his arms. Somewhere, a clock ticks, and Regulus waits. “Have you met Voldemort personally?”

“Yes.” The answer is pulled from his throat, a choking gasp, and Regulus can’t stop it. Doesn’t even have time to think. He realizes what’s happened a second too late. His brain is all panic, grappling for some self control. He stands quickly, dropping the mug and hearing it shatter on the ground at his feet.

Dumbledore leans across the table. “Have you spoken? Has he given you instructions?”

Regulus moves to clap a hand over his mouth, but it’s too late. “Yes, we have.” And, “Yes, he has.” Again, the words are ripped from him with no choice. 

He covers his ears and backs up quickly. He can’t breathe- can’t think. 

Fuck. 

The tea.

It must be. 

He stares in horror at the shattered pieces on the floor.

Regulus knows the feeling well. It’s a little too familiar. Nights spent hunched at the dining room table, answers getting torn from his chest like organs. 

Veritaserum.

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