A/N: I'm very excited to share this new story with you all. It will be 4 chapters, released weekly on Fridays. As ever, this is a work of fanfiction and I am not the original creator of these characters.

Some notes on content before we start: Rating is M, for language and sex. This is a story about infidelity. There is also a large age difference between characters in a relationship (both are adults).

I hope you enjoy!


Guilty by Association

Chapter 1.

Sirius Black is sitting at a grungy muggle bar in East London, waving down the bartender to get a third refill of his whisky. He hates the stuff, but it's better than nothing, and tonight he's not up to going to a place where he can get a proper firewhisky.

He's been talking to a woman, he still is technically, though he's not actually listening to a word she's saying. He thinks her name is something like Sherry or Cheryl, but it could honestly be Rebecca for all he knows. He figures he'll have a couple more drinks, and when he's properly wasted, he'll fuck her in the bathroom and never see her again.

Sherry/Cheryl/Rebecca is about his age, so early forties. She's blond, but probably not naturally so. She either thinks he hasn't noticed the line on her left hand from where she's taken off a wedding ring, or she knows he's noticed and she doesn't care.

"So anyway, I mostly work in the modern art division now, but I hope to get back into antiquities within the next couple of years. When you take time off for kids, your career's just never what it used to be…" she trails off, registering for the first time that he's not paying attention. "What do you do again?" she asks him.

He likes the use of "again". He obviously hasn't told her, but she's being polite, pretending that they've known each other for longer than 15 minutes. Pretending that they don't both know exactly how this night's going to go. The politeness makes everything much more palatable.

"I sell motorcycles," he says. It's not a lie.

"Oh really? How fascinating! What kind?"

"Used ones. Mostly Harley's." There's the lie. He sells flying motorbikes that he designs himself, but he can't tell Sherry/Cheryl/Rebecca that.

"I've always thought they were so cool. If only I weren't too scared to ever ride one!" She laughs, high-pitched and grating.

He wonders how long they'll do the conversation thing, seeing as that's not why either of them are there. He appreciates the politeness, but he has his limits.

Sirius hasn't always been this much of an asshole.

When he was at Hogwarts, he'd been a decent kid. Okay, so he and James had been pretty awful bullies sometimes, and okay, they'd done a lot of illegal magic, but they'd never seriously hurt anyone.

Another lie.

Of course they'd hurt people.

Snape, for one.

Peter, for another. Fucking Peter. Years of neglect, demeaning comments, and stringing him along had directly led to James and Lily's deaths and his own twelve-year imprisonment. He hadn't even realized at the time how cruel they'd all been to him, probably because they'd loved him tremendously. You never think you could hurt someone you love so much without even trying.

That was slim consolation. He'd been a terrible bully and a worse friend, and he hadn't even meant to be.

It had come naturally to him.

Sirius takes a long sip of his drink. He's getting near the bottom of yet another glass, and he's telling Sherry/Cheryl/Rebecca a half-true story about the time he had to fish his motorbike out of a river. He's told this story enough times that he doesn't really have to think about it. It's a funny story, and he uses the laughter as an excuse to lean a little closer and touch a hand to her upper arm.

Maybe Sirius has always been an asshole, but he hasn't always been this bad — this calculating, this disrespectful, this selfish.

He's always been terrible at relationships. Even as a teenager, he'd had issues with commitment, intimacy, communication, a bad temper… Back then, he'd blamed his mother for all of it.

These days, he still blames his mother, definitely, but he also blames two wars, the deaths of all his closest friends, and twelve years of his soul being slowly consumed by demon prison guards.

He's read that trauma can fuck with your sense of morality. Or something like that.

Anyway, the point is, he knows he's become a force for pain and destruction in the world. He thinks it's probably too late for him to change now, so he just tries to limit the damage, contain the fallout.

That's why he comes to muggle bars. If he's going to do terrible things like sleep with other people's wives whose names he hasn't even bothered to learn, then he can at least have the decency to do it where he won't run into anyone he knows. Where he won't have a chance to hurt anyone he loves.

He downs the rest of his drink, signals for another one. That's the other reason he comes to muggle bars. He doesn't like to drink at home, not where Harry can see him, but not drinking is not an option.

Because he needs to cover the pain with something. All the losses he's suffered, all the nightmares he still has, the fact that every awful thing that's ever happened to him has been entirely his own fault — it becomes unbearable. Literally too much to bear. Too much to feel.

So he covers the pain in a two-step process:

It starts with emptiness, from alcohol. He drinks until he feels nothing.

It ends in pleasure, from sex. He fucks until he feels something other than pain — something good, even for just a moment.

He recognizes that this is all incredibly unhealthy. And yet he keeps doing it, because if he doesn't, he's not sure how else he'll cope. If he doesn't do this, he doesn't know how he'll keep getting up in the morning.

For now, he and Sherry/Cheryl/Rebecca are still going through the motions. The flirting's a bit more direct now, the touches lingering little longer. He brushes a piece of hair behind her ear and leans in close.

"Could I get a whisky, please?" says someone who's standing just to the other side of him.

Sirius freezes. He knows that voice.

"Make it a double," she adds as an afterthought.

For a moment, he considers staying where he is, not turning his head, and hoping she goes away. But he's curious. He has to know if it's really her.

So he turns around.

"Ginny?" he blurts, at the same time as she says, "Sirius?"

They look at each other. She has this stunned, guilty expression on her face, like a wolf caught in the moonlight. Her mouth hangs open, just a little.

He thinks that he should say something, make a joke or ease the tension somehow, but then he realizes that Sherry/Cheryl/Rebecca is still lingering on his other side, watching everything.

"I'm sorry, er —" he starts, turning towards her again.

"Natalie." Huh.

"Right, Natalie, of course," he says, flashing his signature apology smile. The McGonagall Melter, James had once called it. "I'm so sorry, but I've just run into an old friend, so, um…"

"Don't worry about it! It was lovely to meet you." She takes her drink and stands, patting him on the arm as she goes. Her friendly tone is slightly undermined by the furrow in her brow. She looks as if she's trying to understand how the twenty-year-old red-head standing at the bar could qualify as an "old friend" to someone like Sirius. It's not an unfair question.

Ginny drapers her jacket over the back of Natalie's chair and sits down. "You didn't have to tell her to leave, you know."

"Meh," Sirius says noncommittally. "It's not a big deal. We just met."

"Really? You seemed so close to me," she says, sarcasm in her voice, mouth twisting up into a smirk. Her hair looks darker in the dim light of the bar than usual. More auburn than Weasley red.

Sirius makes an indistinct grunting noise. "What are you doing here, anyway?"

"Having a drink."

"Here?"

"I fancied a change of scenery." She shrugs airily. She gives him a look that says I know you know I'm lying, and I don't care.

She downs the remaining half of her drink in a single swallow and waves for the bartender.

"Bad day or something?" Sirius pesters her.

"Or something," she agrees.

They drink in silence for a moment. Sirius is well and truly drunk now, and he doesn't know where to go from here. He and Ginny rarely talk; he can't think what to say to her.

So he ends up telling her the same story he just told Sherry/Cheryl/Rebecca - or, whoops, Natalie. He tells the entire story this time, magical details and all, about how when he was nineteen, two weeks after getting his first bike working, he had to swerve to avoid a hot-air-balloon full of muggles. He ended up in a river.

His levitation spell wasn't powerful enough through the water, so he called James to come help him get the bike out. James showed up with a canoe, just carrying it on his back when he apparated in. Sirius still didn't know where the canoe had come from.

It was hilarious at the time, and Ginny laughs in all the right places when he tells her about it.

"Do you miss it?" she asks.

"What, falling into rivers?"

"Back then, before the first war. Do you still miss it?"

"Every day. I miss it every day, of course I do. James, Lily, Remus, fucking Peter, my damn brother Regulus." He may miss them, but there are still certain names he can't say without the preface of a swear word. "They all could have had such good lives. I could've had a good life. I miss imagining a future other than this." He gestures broadly.

He hears how bitter he sounds when he says it. His honesty is surprising, even to himself, but in the moment he doesn't regret being open. It feels good to talk about it, for once.

"So it never goes away?" she asks. "I keep thinking it will one day. That someday I'll stop wondering what could have been and just accept it."

He shakes his head. She swallows more of her whisky and he watches her throat as it goes down.

"Tell me about it," he says.

"What?"

"Your bad day or something."

She sighs. "It's nothing. It's just that…" She shakes her head. "It's nothing. It's stupid."

"It's clearly not nothing."

She glares at him. She downs the rest of her glass. Then she talks.

"Fine. It's all exactly like I thought it would be, okay? I got everything I ever wanted. Harry, playing for the Harpies… My life is bloody perfect."

"So the problem is…?"

"I think I'm supposed to be happy."

"And you're not?"

"And I'm not," she agrees.

"Well, if it makes you feel any better, I haven't been happy for twenty-one years."

She stares at him through the sides of her eyes, sizing him up.

"That's longer than I've been alive. So, no. That does not make me feel better."

He laughs. "Fair point. But you didn't get your brain rotted by dementors for over a decade, so probably you still have a chance. Or something."

"Or something," she echoes. Sirius notices for the first time that Ginny's black dress has lace detailing along the neckline.

"Ginny, why are you here, really?"

She shrugs. For a moment he thinks she's going to avoid the question like she did earlier, but then she says quietly, looking at her glass, "Same reason you are, probably."

At first he doesn't get it. Then he thinks she doesn't get it. Then he thinks of course she does, she's not an idiot, but he still needs to clarify, so he asks. "You do know why I'm here, right? You saw me talking to that woman?"

"I did see you talking to that woman."

"So… you're saying… you were here to meet someone? For…"

"Maybe. Yes. No. I don't know," she says. "Yes, maybe."

He finds he's too drunk to deal with all this vagueness and suggestion. So he just says it. "If I hadn't been here, you'd be cheating on Harry right now? Unless you two broke up and he didn't tell me about it."

"We didn't break up."

"That's not an answer to my question."

"Isn't it?" She looks him in the eye defiantly when she says it.

"Well, fuck. I guess it is."

Sirius, yet again, does not know where to go from here. She keeps surprising him.

"Am I a terrible person?" she asks.

"You're a better person than me."

She shakes her head. "I don't know about that."

"Any terrible thing you've done, believe me, I've done it at least twice."

"So I have time then," she says darkly, and they both laugh a little.

If either of them had anything left in their glasses, they'd both be taking a sip, but as it is, they're all empty. Instead, Ginny does another surprising thing.

She kisses him.

He starts to pull away, to say stop, we can't do this, we're drunk, this is wrong, we'll regret this, but then he tastes whisky and peaches on her mouth, and all he can think about is the lace on her dress and how her hair looks in this light, and he forgets to stop.

He's still forgetting when a minute later she stands and whispers in his ear. "Take me somewhere."

He'll realize later that she probably meant somewhere nice, somewhere away from here, but right now he's drunk and so he just takes her to the bathroom. He throws some money down on the counter of the bar and takes her hand. Sirius pulls her through the loud, dense crowd and they find their way to a tiny, dimly lit, single-stall bathroom.

The door closes behind them and he presses her into it, one arm wrapped around her lower back and the other bracing himself against the frame. Then he kisses her.

She links her hands behind his neck as if to trap him against her, pull him closer.

There's an earnestness to the way she's kissing him. Maybe it's the youth, or maybe it's the whisky, but her mouth on his feels honest. Optimistic. And Sirius is a die-hard pessimist, but even he feels a little bit hopeful.

He thinks for a second about Harry, and how even though he's seen the absolute worst of the world, his godson is one of the most optimistic people he's ever known. Maybe that optimism is something he shares with Ginny.

It's enough of a reminder of the situation that Sirius inches his mouth away from hers for half a second.

"We shouldn't do this," he says, but by the time he's finished speaking his mouth is already back on hers.

"I know," she responds, but she doesn't stop.

He slips his hand lower down her back and keeps going. He feels her shudder a bit as he pauses over her backside, digs his fingers in. She arches her hips further against him, and he slides a hand under her skirt. He spreads his fingers wide over the back of her thigh, desperate to touch as much of her as he can, and she hitches her leg up, wrapping it around his.

They're pressed so close together now that he knows she can feel him. He wants her to. Wants her to know how hard he is for her.

He has the wild thought, as they fumble against the door, that he may be an asshole, and a terrible person, and destined for hell, but maybe he's not alone. Maybe he'll see her in hell someday.

Ginny touches a hand gently to his stomach, too gently, so gently that he can barely feel it, yet he feels it in his entire body. It's too much for him. Too tender. He pulls her urgently away from the back of the door, still locked together, and angles her toward the sink.

She gets what he's going for and hops up onto the counter. She wraps her legs around his waist and threads her fingers into his long hair. She pushes his head down a little, taking charge.

Sirius presses his lips against her collarbone, runs his tongue over the hollow of her throat. Her skin tastes warm, salty and sweaty.

He pulls at the fabric of her dress, folds away the cups of her strapless bra, steals a moment to look. And fuck, she's perfect. Not that there's really such a thing as imperfect when it comes to breasts, but still. Perfect.

He feels unexpectedly nervous as he brings his mouth to her nipple, because all of a sudden this feels real. They're really doing this and he wants it to be good, wants it to be right, even though that's an impossible goal, since this is entirely wrong. It's all wrong, wrong for so many reasons he can't even list them all, but at this moment the actual impossible goal would be to find it in himself to care about a single one of those reasons.

Because at this moment his mouth is on Ginny Weasley's tit and she's gripping her hand tighter into his hair and she's letting out a soft little moan and it's incredible. It's all fucking incredible.

He bites down gently and she whimpers.

Sirius needs to kiss her again. When he does, it's a spectacular, open-mouthed, tongue-heavy kiss, and he hopes he's conveying to her what he's feeling, which is: everything.

Everything is not enough.

He pulls away and grins at her, flicking his eyes downward, asking for permission.

Ginny grins back, biting her lip, and he crouches down, putting his head between her legs. Her dress has already ridden up around her hips, and she shifts her weight on the sink, helping him as he takes off her knickers.

He takes a good look and the view is fucking spectacular. Not just what's between her legs, though that is — like the rest of her — perfect. But everything, the way her hair's come loose, and her makeup's smudged, and her dress is all askew, covering nothing.

He puts his mouth on her and tastes what he hadn't realized he's been longing for since she sat down next to him at the bar. He laps at the folds of her cunt and swirls his tongue around and slips it inside her. He replaces his tongue with a finger, then two, and he loves the way she flexes around him, drawing him further into her.

He works his tongue over her clit and he works his fingers inside her, and he hears her moan as she digs her hand into his hair again, gripping tightly. It's the prettiest sound, and he wants to make her sound like that again and again.

Sirius is good at this. He's had lots of practice. He's done this a thousand times with dozens of women, and he knows what he's doing. But also, he's never done this before, because it's never been Ginny before.

This is fresh and new and exciting and amazing and holy shit her body is convulsing under him. Her hips buck and she comes so hard she practically falls off the counter.

He's looking up at her right after, so he sees the exact moment her blankly blissful expression changes to panic.

"Oh my god, what just happened?" She's standing up and fumbling around, straightening her dress. "This can't happen, this can't be happening."

Sirius takes a few steps back, putting distance between them, as reality crashes into the room.

"Ginny, I — " he begins, but he doesn't actually know what to say, so he just leaves the sentence hanging.

"Where are my fucking underwear?" she says, a hint of hysteria in her voice.

He vaguely remembers throwing them to the left when he took them off, so he looks in that direction. He finds them and passes them to her.

"Thanks," she says softly, looking absolutely stricken. He places a hand on her shoulder, trying to be comforting, but she flinches away from him.

"I'm sorry," he says. "Fuck, I'm sorry. You're right, this shouldn't have happened." And he is sorry. This shouldn't have happened.

"And it never did," she says firmly, grabbing her bag and heading for the door. "I have to go."

She opens the door and practically runs out of the room. He watches as she rummages, probably looking for her wand. He knows that as soon as she rounds the corner, she'll apparate as far away from him as she can get.

Sirius closes the bathroom door and leans against it, right where Ginny was mere minutes ago. This is the problem he has with feeling. Feeling good doesn't last. One minute he was feeling better than he can ever remember feeling, and the next he's here. 'Here' being standing in a dirty bathroom in a muggle bar, having just gone down on his godson's girlfriend, who is, by the way, half his age. Oh, and also he's just betrayed Harry, who is literally the only person in the world that matters to him.

Eventually, Sirius disapparates. He goes straight from the bathroom into his bedroom and collapses onto the bed, but he doesn't sleep. Instead, he lays awake, staring at the ceiling, ashamed of how he can't stop thinking about Ginny and the way she looked when he was crouched between her legs.


Aaand that's chapter one! Please let me know what you think!

Title inspired by the song Lethal Combination by The Wombats.