How To Have An Illicit Affair

Harry Potter - J. K. Rowling
F/F
M/M
G
How To Have An Illicit Affair
Summary
A few months after Sirius Black leaves Grimmauld, Regulus Black is forcably outed by his parents and inevitably gets kicked out. From then on, he has to fend for himself. A curious James Potter makes his way to the astronomy tower one night and the rest, as they say, is history.
Note
hello!! I'm not one for introductions but i hope you enjoy this as much as i am enjoying writing this. A few things before we dive in - my prounouns are he\him and I'm a guy so please mind that when commenting.Also feel free to point out any grammar mistakes in my English since it isn't my first language (yes, it’s one of those fics):) Also, I will be using french occasionally, which is my third language so please feel free to point out any mistakes as well if you see them. Updates once / twice a week. love y'all and please comment your thoughts, i'd love to hear them ADDED NOTE: I made a playlist for the fic and listened to some of it while writing. https://open.spotify.com/playlist/7sEvTOVP8WeyWDVKpClKy7?si=13f9350d06864668
All Chapters Forward

Everybody Talks

“Oh, oh, oh-”

 

“Shhh. They’ll hear us. Be quiet, won’t you.”

 

A small whimper came out of Sirius’ mouth.

“As I recall not too long ago I was ‘loud and obnoxious’?”

 

“Well, that was before I got my hands on you.”

 

And then Remus goes down, and it all goes blank.

 

For a few seconds, of course. 

 

Before the door opens. 

 

“Oi, what’s all the- OH DEAR GOD.”

 

Remus shuffled on top of him and almost fell trying to get off of him. Maybe it wasn’t smart, hooking up in their shared dorm room in the middle of the day. But then again, Sirius was sure that Peter had gone to watch James in practice. So he coaxed Remus into giving in and risking it and, well. Look how that turned out.

 

“Oh my eyes. My eyes.”

 

“Pete, we’re-” Remus said hurriedly, trying to put his shirt on and failing to find the neck of it, turning it inside out.

 

“My. Eyes.”

 

“Come on, Wormy. Don’t be a buzzkill,” Sirius laughed, earning himself a deadly right hook in the ribs from Remus. “Oi!”

 

“Shut up, you drama queen,” Remus hissed, “Look. I think we broke him.”

 

And they both stared at Pete for a moment, his eyes wide and legs frozen in the same place he entered. 

 

“Pete?” Remus said carefully, sounding mostly amused and slightly concerned. “You good?”

 

“He’s broken, I’m telling you. They’ll write it on my tombstone now, I can see it. ‘Sirius Black: killed his own best friend, gave ridiculously good head.’” 

 

Remus tried, failing, to mask his grin, “I’ll be the judge of that last one.”

 

“Oh, god,” Peter quivered, backing out. “You can… go back to sucking the soul out of his neck. I’m happy for you, guys, truly. But from far, far away. Very far away. I’ll- I’ll just go. Well. Goodbye.”

 

And with that final note, Peter backed out of the door, walking slowly as if he was stepping on eggshells, and then stormed out and closed the door.

 

“Huh.”

 

“Are you okay?” Remus asked, a glimpse of worry in his voice. “I know you weren’t ready for…” 

 

“I’m great actually. This was… fun.”

 

“Fun?”

 

“So fun.”

 

“Care to do it again sometime?”



★ 



And so, Remus and Sirius formed a plan. They’ve talked about it before, how they would tell their friends about them. But first, they had to figure out what they were. 

 

They’ve been dating for over a month now, but it took a while for Remus to start trusting Sirius again, and for Sirius to stop walking on eggshells near Remus. 

 

When they started, right after the fighting and kissing in the cupboard part (which they did often, by the way, as storage closets were common in the hallways and no one ever cared to enter them), they went back to the dorm room.

 

The banter died down as they came in the door. The room was empty, but the silhouettes of their previous fight lingered still. For a moment Sirius wondered if it was real, if he actually confessed to Remus about his feelings, or if it was merely a dream in which he was actually brave. When he pinched himself, he didn’t wake up. Real, I presume. 

 

Remus sat down on the bed and looked at him with wandering eyes, quizzical, even. He seemed confused.

 

Sirius took a deep breath and sat beside him. 

 

They were silent for a few moments. 

 

“Why did you tell me?” he mused softly after a few moments. 

 

“Sorry?”

 

“What made you decide to tell me?”

 

Sirius swallowed. 

 

“Oh, a couple of things, actually. First it was Regulus. We had a conversation a while ago, it wasn’t about… us, specifically,” he swallowed, “But I think he knows. Maybe I just needed that slap in the face.”

 

“What did he say?”

 

“He said I don’t live there anymore. That we don’t live there anymore. It was a few months ago, right after christmas. I think he was trying to convince himself as much as me. But it made me think, you know.”

 

“Oh?” Remus said, as if he was hungry for more. He was very quiet.

 

“My mother made me, and I was trying to make it up to her,” he said simply. He turned quiet and continued after a few moments. “I think she knew how I felt about you. How I feel about you now. And she made me pay for it.”

 

“How could she know? I’m assuming you didn’t tell her…”

 

“Walburga is very good at legilimency,” he said bitterly.

 

“Sirius, I-”

 

“That’s not an excuse, for me, but an explanation. When he said that, I just thought to myself, ‘man, I’m not fourteen anymore’, and I was sad, until I remembered.”

 

“Remembered?”

 

“Remus, I’m not fourteen anymore. I can kiss you if you let me. And I will.”

 

Remus looked at him as if he might burst any moment now. 

 

Sirius knew exactly how that felt. 

 

“Well, if you insist…”

 

Sirius was too gentle at first, not as he usually was. He shook slightly when Remus touched him, making him back away, “Are you okay?” he asked gently. 

 

“Yes. And also no,” he laughed nervously, “I want you. So bad. But I’m scared.”

 

“Of what?” Remus asked, his voice softer than Sirius has ever heard it, his palms holding Sirius’, caressing them.

 

“Her. And you, sometimes.”

 

“Me?” Remus’ voice was small. 

 

Sirius only took a few moments to understand why. “NO! Not because of that. Never that. Take that thought out of your mind.”

 

Remus smiled softly, but fakeness was hidden in it.

 

“I guess I just wonder.”

 

“About what?”

 

“Do you really… I mean, do you really like me? Like that?” he asked, embarrassed of having raised the question.

 

“No.”

 

“No?” he asked weakly. 

 

“I don’t like you, Sirius,” Remus said simply, “I love you.”

 

“Oh.”

 

And then Remus came closer and pressed a kiss to his lips, sealed as they were, he felt the softness in his touch and rejoiced with it. 

 

And then came another, and then another.

 

And Sirius isn’t fourteen anymore, and he has allowed himself to love and be loved.



It still wasn’t as simple as it could be after that. 

 

Sirius was still scared of hurting Remus. He would wake in the middle of the night of wicked dreams, he would hear her voice calling for him to come home. Walburga was a siren, a deafening one, and he came closer to her without fail when she gave even the slightest hint that she could love him. That she had it in her. 

 

As a siren, she was half mythical beast and half human, beautiful as any Black even within the pain she caused her children. As he awoke, sweating and panting, he clinged to Remus’ warm body and his steady breath, his brown curls swaying gently on Sirius' shoulder from the wind that came from the window. He seemed peaceful as he slept, never in the pain he suffered when awake. 

 

Maybe all of the Blacks were sea sirens, he thought to himself as he stared. Mythical, horrible, seductive and hungry for flesh, but graceful and painfully aware of their beauty. And they were beautiful, in a way you couldn’t miss even if you tried. Their beauty spread across stars and galaxies, and as sirens, they would cause the men at sea to trip and fall in order to get to them.

 

But Sirius still wondered what happens after. After Remus got to him. Would he learn of his nature and leave, or would he be blinded by all things fake not to see how Sirius was from inside - rotten, a boy who carries his mother’s eyes, and her anger, and her fears? 

 

On some nights he could have sworn he’d felt her pain, her gut wrenching screams of grief, her beatings hit his body, growing harder and harder every time. Even safely tucked in far away Scotland, even in the arms of the boy he loves, has loved for so long, she was there. 

 

Some days, he looked forward to forgetting her face and the sound of her voice. To perhaps walk past her on the street, and have both not recognize one another. But throughout his fantasies, he knew he would know her. He would know her in death, in the end of the world. So on some days, Sirius didn’t think about his mother, because he already left and there was nothing to be done. And on other days, he would almost pack a suitcase, just to go back, just to see if she could change her mind. 

 

And on some days, Sirius hated Remus. On most of them he loved him, feeling the breath of life whenever Remus touched him or looked at him. He loved him all the same, even as he hated him, even as the thought of her maimed him harder than the scars she gave. 

 

It took him a while to touch Remus back, even if he wanted to more than he wanted to breathe. Even with the memories of his twelve, thirteen, fourteen and fifteen year old self, craving for every touch Remus could offer, waking in the middle of the night, and craving it in sweat. 

 

It took a little longer for him not to be careful with every step he took around Remus. Remus was offended by this at first, and went softer as Sirius crookedly explained it to him. Sirius could tell he didn’t understand, but he really, really tried, and that meant something.

 

It took a while longer for him to retreat from being scared of touch to him being loudly, and proudly starved for it. To him waking Remus in the middle of the night, or staring at him shamelessly even with everyone around. Some part of it was fun, the chase, the way he knew that only two people in the world know what really goes on between Remus Lupin and Sirius Black, and he was one of them. He relished in the way Remus continued to be his, after every nightmare and every scar that was revealed, in the way he became weak under his touch, and the way Remus did the same. He grew more and more confident in every little heaven sent to him by touch, and every little hell that rushed through him when he awoke from a nightmare and Remus was still sleeping beside him. 

 

A confidence that became staying over at the dorms to hook up with his boyfriend during James’ quidditch practice, and be caught by Peter. 

 

He thought he’d feel empty, if anyone found out. Not because it was Remus. But because it was a boy, and Sirius was notorious for many things and has grown a reputation and a taste for everything other than that. Maybe because it was his best friend, and a part of him thought it would change things. Maybe because despite knowing the mere idea is ridiculous, he feared of James’ reaction. James, who never gave him any reason to believe that he would, James, who comes back with hickies and disappears at parties and goes on and on about a mysterious beautiful boy whenever he got drunk in the last few months. So maybe it was all a little ridiculous. 

 

But then Peter came in. And it wasn’t scary, it was… hilarious. And seriously fun. So he thought back to what Remus said that day weeks ago. Not without fucking with them a little bit first. 

 

And that’s how Sirius and Remus came up with their little evil plan, to terrorize every single one of their friends and come out in the process.

 

 

★ 

 

 

The next one had to be James, because Peter was very, very bad at keeping secrets even if he wanted to, and Remus and Sirius were sure that if he wouldn’t tell James, he'd dig it out of him in no time.

 

And so this time they planned it more carefully. Well, they didn’t plan it, Remus did, evil mastermind that he is. Before it happened Sirius was nervous, but also excited for James to know already. 

 

He was ready. 

 

So, the three of them sat in their dorm room playing exploding snap together, when Sirius and Remus picked up a fight over nothing. 

 

I mean this literally, because James truly did not understand what they were fighting about. 

 

“Oi! what’s going on?” he said when he came out of the bathroom to find the two of them bickering. 

 

“YOU BELLIGERENT LITTLE-”

 

“ME? YOU WERE THE ONE WHO STARTED THIS, YOU UNBELIEVABLE PRICK-”

 

“OH, I COULD HEX YOUR FACE RIGHT OFF, YOU-”

 

“GO ON, THEN!” Remus yelled. He was a very convincing liar, apparently, because James seemed genuinely concerned and tried relentlessly to tear them apart. But Sirius looked in his eyes and saw mischief in them, and almost couldn’t stop himself from smiling.

 

“WELL, YOU-” Sirius said when he was stopped by Remus jumping and kissing him with so much force that his knees buckled. 

 

“OI!” James said, half screeching, “Oh, OH.”

 

When Remus tore apart moments later he ruffled Sirius’ hair and then looked at James, his face completely nonchalant as if nothing happened, “Alright?”

 

“ALRIGHT?!” James yelled, “I- NO!”

 

“I think he doesn’t like us fighting, Moony,” Sirius said solemnly, “Do try to keep your tone down next time you start fighting me, won’t you?”

 

“Oh, you utter tosser, I can use whatever tone I want with you.”

 

“I am so, so confused,” James said, eyes shot wide and expression more dumbfounded than the time Remus tried to explain how telephones work to him.

 

“Whatever did we do that made you so clueless?” Remus asked, faking concern. “Do you know what it might have been?” He turned to Sirius.

 

“Not a clue, Remus.”

 

“Stop. What’s- what? You’re together? Like, together-together?”

 

“No, he uses me for sexual favors and tells me I’m worthless,” Remus said in all seriousness, folding when Sirius gives him a proper right hook in the ribs for that. “Yes. We’re together.”

“Fucking finally. And god, must all of your plans entail sex?” James asked Remus, half confused and half amused. 

 

“A master never reveals his secrets,” Remus smirked.

 

“What plans?” Sirius asked, confused. What plans?

 

Remus winked at him and ruffled his hair again. 

 

Is Sirius dating a psychopath?

 

“Wait. Wait. How long have you two…”

 

“New year’s day,” Sirius replied.

 

“Blimey. Are you happy?” he asked, his tone serious and his eyes examining them both.

 

“Yes,” Sirius smiles. Remus nods in agreement. “Yes, Prongs,” he said, “We’re happy.”

 

“Does anybody else know?”

 

“Only Pete. And by accident, really. He, er, walked in.” 

 

“Oh. Poor Pete,” James said, “I only assume you scared the piss out of him?”

 

“You know me well, Potter,” Sirius smirks.

 

“So I’ll leave you two to finish what you started. And for what it’s worth, Moony, every time we hang out you scare me even more.”

 

James smiled and looked at them, almost like a proud parent. 

 

Sirius knew that look from Effie. 

 

When his eyes saw their hands intertwined he stopped and lingered for a moment. It was so short that Remus didn’t notice it, so slight that it almost escaped Sirius’ eye, but he saw. At first, he thought it was sadness. But then he knew. 

 

James was jealous. 



 

★ 






The next one on their mission wasn’t one person, but two people. Both were incredibly crucial to it, and were to be told separately by Remus and Sirius.

 

Regulus and Lily. 

 

They talked about it a lot before, and decided that they should tell them separately. It was important for Sirius to tell Regulus alone, and for Remus to talk to Lily in length about everything. From their many conversations, as there is a lot to catch up on when you are estranged and stuck in a more-than-friendship-and-less-than-together relationship as it turns out,Sirius found out that Lily knew about what was going on between them. 

 

Not everything, as Remus concealed many parts of himself, and at times was still cautious with his friends as he was when he was eleven. But she knew, whether she had guessed it, or saw it one day and realized it, Sirius did not know, but what he did know was that her relationship with Remus was one of the most important things to him. She was dear to him as a sister, and he was dear to her as a brother, and in their shared glances and the way they spoke gently and kindly of each other Sirius saw his and James’ reflection.

 

And Regulus was a different thing entirely, because everyone knew the situation was fairly… complicated, even if they couldn’t even begin to grasp just how much. He loved him dearly, and through his eyes he could see the reflection of the joy they once shared, and were beginning to come to know again. This would be a leap of faith, not in trust that Regulus won’t react badly or would be indifferent, but in Sirius sharing something with him that has to do with his future, and not their past. 

 

Recently, Regulus has been looking more and more withdrawn. He noticed it a few days after the last match between Gryffindor and Slytherin, and it hasn’t seemed to stop since. He would notice it in the hallway, when his friends would talk around him while he was deep in thought, his eyebrows furrowed and his lips pursed. During the meals, where he sometimes barely ate and was not present during others. In the dark circles under his eyes, and the hunger present in them whenever he spoke to him. What he was going through, whatever it was, was beyond Sirius’ understanding, and caused him to wonder relentlessly. At nights, he would watch the map and see him go up to the astronomy tower and pace for hours on end, until sunrise came and he left with it. Some days, he wouldn’t even be on the map - which worried Sirius at first until he figured that Regulus may be going to the dark forest, the reasons of that would be, of course, unknown to Sirius, but nonetheless explained the mysterious disappearances. 

 

“Hey, Reg?” he said in the hallway before class, about a week after they told James.

 

“Yeah?” Regulus turned around. 

 

“Can I talk to you for a minute? I need to tell you something.”

 

Regulus looked at him for a few moments and then, to Sirius’ surprise, smiled knowingly before he said, “Of course. Where do you want to go?”

 

“Astronomy tower,” he said without thinking. He wondered.

 

The smile faded a little from Regulus’ face but he nodded, and they went up.



“Go on,” Regulus said when they made it up. They were leaning on railing and looking over at the sky. The day was bright and the sun hid slightly behind a cloud.

 

“You know Remus?” Sirius said and looked over at Regulus, nervously.

 

“Yes, Sirius. I know Remus,” he said sarcastically and continued to look at the sky ahead of him, a tight smile pressed to his lips. 

 

“We’re… well, Remus and me, we’re together.”

 

His smile remained. 

 

Sirius felt as if a stone came off his chest. 

 

“I know,” he answered simply. 

 

“You know?” Sirius asked, surprised. 

 

 “Are you happy?” Regulus asked and ignored the question, his face turning to look Sirius in the eye. 

 

“Yes,” Sirius answered, almost in a whisper - as if his happiness was a secret. “How did you know? When?”

 

“First of all, I have eyes. And I use them, if you can believe it,” which made Sirius roll his eyes, before Regulus’ face turned serious again. “And I just looked at you, and I knew. It’s amazing to witness. What you two have.”

 

“You really think so?”

 

“I know so,” Regulus replies, quieter now, as if he fears it, “You look happier, Sirius. I’m happy for you. You of all people deserve it.”

 

And then his face turned away and watched the sky again. And there it was again, the hint of an emotion not foreign to him or his brother, unresolved and harsh on his Regulus’ face.

 

Jealousy. 

 

He wondered what it could mean. 

 

Was Regulus really this unhappy?

 

“Regulus?”

 

“Yes?”

 

“Are you happy?” he asked carefully. 

 

Regulus smiled. Not as he did before, but with a hint of care and resentment all the same, “I don’t know.”

 

And in his eyes Sirius could see that he wasn’t lying. 

 

“Do you want to be?” 

 

“I don’t know.”

 

And again, Sirius didn’t know what to say. 

 

“Does it help that I wish you were happy?” Sirius asked.

 

“No,” Regulus answered in severe honesty again. “It’s good to know, though.”

 

They stood there in thoughtful silence for a few minutes before Regulus said he had to go to potions. 

 

Before his figure disappeared in the staircase that leads back to the castle, he turned around. 

 

“Tell Lupin that if he hurts you I’ll make him wish he was never born.”

 

Sirius grinned. 

 

His smile reaches his eyes.





From what Sirius gathered, Remus and Lily’s conversation went very well from the way Remus came back grinning to the dorm. 

 

“Good?” Sirius hoped.

 

“Very,” Remus answered before he climbed over Sirius and made him lay on the bed. On top of him hovered a very happy Remus, who pushed his lips fiercely to Sirius’ and made him gasp in surprise before he returned the kiss. 

 

“What did I do to deserve this? Not that I’m complaining, or anything,” he said, laughing in between kisses.

 

“I’m happy, if you can believe it,” Remus rolled over and laid beside Sirius, his shirt climbed up and revealed the scar that lashed its way across his torso. 

 

“I can see that,” he mused softly with a wide grin. “I was caught off guard at first.You always look so tortured, did you know?”

 

“Dick,” Remus pushed him off the bed. Sirius landed with a thud. “I’m serious.”

 

He looked down at Sirius from the bed.

 

“Say it and no blowjobs for a month.”

 

“I wasn’t saying anything,” Sirius said innocently and climbed back up to the bed. He sat against the headboard.

 

“It went well,” he said, “With Regulus.”

 

“That’s good. Why do you sound like it isn’t?”

 

“I think something is going on with him. He’s not happy.”

 

Remus turned quiet for a minute before he said, “I don’t know Regulus, but from what you told me about him, he’s strong. I think he’ll be okay.”

 

“I want you to know him, you know,” Sirius said.

 

“You do?” Remus sounded surprised. 

 

“He’s my brother, and you’re my… you’re my boyfriend, I think.”

 

“You think?” Remus said, amused. 

 

“We haven’t really… had this conversation. I’m not good at this part, you know that better than anyone,” he said, embarrassed.

 

“I do,” Remus said softly, “And I am. Your boyfriend, I mean.”

 

Sirius kissed him.





When Sirius walked into the great hall for breakfast the next day, there was an empty spot for him next to where Remus was sitting, and all of his friends were looking at him. 

 

Mary was smiling her knowing smile - that he came to know very quickly as he began to know her, because she is almost always right -  so he guessed Lily told her. He smiled back at her when she said, “I knew you’d come around.”

 

Remus choked on his toast and Sirius smiled.

 

Lily gave her a shove which made Mary turn to her, “Hey! I’m right, you know. It’s about damn time.” 

 

Sirius smiled to himself.

 

“You alright, Pete?” he said and turned to Peter, who looked oddly calm considering the fact a week ago he saw one of his best friends going down on another one of his best friends. 

 

“I’m good, yeah. I came around on the whole Wolfstar thing,” he said casually and took a bite out of his toast. 

 

Lily choked her laughter next to him.

 

“Peter,” Remus said, cautiously.

 

“Yeah, mate?” he looked up from his plate, mouthful.

 

“What the fuck is Wolfstar?”



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