Want - by Sara's Girl

Disclaimer: I don't own Harry Potter or either of the Blacks. For the record, I wouldn't have killed off either of them *sigh*

AN - This is for scottish_play, my LJ wife-to-be ;) because of her encouraging 'adslfdjflijk' when I first mentioned that I'd like to write some Blackcest. Hope you enjoy, sweetie.

Canon can bite me. I know Sirius wasn't living at home when he was 17, and I know they wouldn't have shared a bedroom, but honestly. Siriusly. I just wanted to write Black!porn. *whimpers*

A polite request: if incest squicks you, that's fine; you know where the back button is. Please don't come crying to me if you decide to read it and then wish you hadn't. 'Kay? For fellow deviants, reviews are adored.

Warnings: where to start? Slash. Incest. Underage [SB-17 and RB-15]. AU. Plotless porn.

**~*~**

Sirius would be the first to admit that he thinks most of that 'a Black should do this, and a Black must do that' stuff is a load of old bollocks, but there are certain areas of the Noble and Most Ancient Black philosophy that coincide with his own.

One of which, one that he believes in wholeheartedly, is that 'wrong' is all a question of perspective, another is that winning is everything, and one more is that he'll be damned if anyone's ever going to tell him that he can't have something. Especially something he wants.

He can't help it if the things he wants are, almost without exception, messy, unclothed and deeply satisfying. All Sirius knows is that his veins practically vibrate with sexual energy. All the time. And he's not sure if that's a Black thing or just a Sirius thing, but it's academic really, because some things just are.

Unfortunately, being philosophical isn't helping his constant state of arousal much at all, and, two weeks into the last summer break of his school career, he rattles around the house with only his parents and Regulus for company, and there's precious little stimuli for letting off steam, even in the solitary fashion.

Until there is. Until he wants. Until he wants, hard, and most unexpectedly.

Sirius prides himself on never allowing anything to take him by surprise, not even that day when he found himself swept up in a wave of desire after watching the curve of Moony's arse in school trousers and the fall of honey-coloured hair across his cheek as he bent to pick up a book. He'd dealt with that.

But this. Well. It's fucking hot today; the air inside and out is like soup, and Sirius has always been useless with Cooling Charms. As he climbs the stairs, he's not thinking much further ahead than shower. Cold shower, possibly, killing two birds with one big, wet, metaphorical stone.

His first step onto the landing creaks like it always does, and his nostrils twitch at the fresh cloud of fragrant shower steam that drifts from the first floor bathroom and into the bedroom he shares with Reg.

Something, he doesn't know what, makes him stick a pin in his shower idea and impulsively follow the sweet-smelling steam until he's silently pushing open the bedroom door with his finger.

And stopping dead. Mouth turning dry and fingernails digging into the splintered wood of the doorframe, his breath stalls in his throat because what he sees turns the want licking inside him into a tidal wave.

It's just Reg, he tells himself. It's Reg. But it's Reg, spread out shamelessly across his bed, towel cast to the floor in a heap, naked. His clean, damp skin is pale and water-sheened, and for the life of him, Sirius suddenly can't remember what it's like not to want to lick those water droplets from his brother's sharp hipbones.

Every muscle in his body tightens as he takes in the head thrown back and the water-darkened hair grazing Reg's pale shoulders in tangled strands. Biting his tongue hard, Sirius lets Regulus' soft little cries and pants fill his senses and his cock; his eyes fix now upon the long fingers moving slowly, languidly over his brother's growing erection. The action is hypnotic and Sirius is so worked up that he barely dares to breathe.

It's Reg, for fuck's sake. He's seen him naked, seen his cock, but not like this. Not flushed and hardening before his eyes in Reg's hand. Disappearing and then reappearing in his closed fist: slowly, teasingly, like he's dragging it out on purpose, and he's enjoying it, too, if the agonised moans and arching of slender hips into his hand and the clenching of fingers and toes into the bedsheets are any indication.

Sirius doesn't drag it out like this; he just gets on with it, but watching this... self-torture, he wonders, squirms, wants—

—fuck. He's so hard, he might just explode. Heart hammering, light-headed, he licks his dry lips and presses a firm palm against his erection.

"Oh, fuck," Reg whispers, lifting into his hand over and over; he's obviously so close and Sirius suddenly registers that he's standing right in the doorway, and if Regulus just looks up, he's screwed.

Barely breathing, Sirius backs up and quietly pushes the door back to its previous position, stepping out into the hallway. He rests his head against the embossed wallpaper and waits, strung so tight he can barely stand it. It's not long before a broken, keening cry reaches his ears, and he closes his eyes and groans.

With some effort, he unpeels himself from the wall and half-staggers into the bathroom. Breathing hard and ragged, he inhales the last of Reg's shower steam and frantically shoves his trousers and pants around his knees, gripping grimly onto the cold edge of the sink with one hand and wrapping the other around his leaking, needy cock.

Sirius isn't thinking. No. Not thinking, just blindly wanting as he wipes the condensation from the mirror with his palm and stares at the smudged reflection of his own lust-darkened grey-blue eyes as he strokes himself; there's no time to drag it out, either.

Those eyes are so similar to Reg's that he can imagine the expression he missed when he hid outside the door and listened to his brother's muffled wail as he came. Sirius is flying now, calloused palm gripping and spreading sticky fluid over his cock—Reg's is a shade smaller but nice, oh...fuck, nice—as he strokes himself to a hard, dirty, intense orgasm right there in the bathroom. His teeth dig into his bottom lip and he forces his eyes open for as long as he can so he can see. Grey-blue eyes. Black eyes.

Fuck. Sirius bites down on his cry and collapses back against the wall, head spinning.

Well. That was interesting, he thinks. After a few minutes, he cleans up and heads downstairs to look for Kreacher; he's always starving after a good wank.

Interesting, he reiterates silently over steak sandwiches in the garden. But it's not as though Reg needs to know about it.

**~*~**

When Regulus slips into the dark bedroom later that night, Sirius closes his eyes and pretends he's asleep, just in case it's one of those rare nights when Reg feels like talking.

The silence, but for a belt buckle hitting the floor and the rustle of sheets, is reassuring until Reg says:

"I know you were there, Siri. I heard you."

Sirius catches his breath because he wasn't expecting that, and because he's getting hard again as the memory tugs at him and replays vividly behind his eyes. Frozen stiff with panic and desire, Sirius politically decides to continue pretending he's asleep.

"Siri?" Reg tries again, hesitant. He only ever uses the nickname when they're alone, and not always then; Sirius bites his tongue to keep from answering to it.

He stares at the wall and wonders what exactly the fuck he's going to do now.

**~*~**

Nothing, he's decided after a sleepless night. He's going to do nothing. Because, OK, he might've been turned on (beyond belief) watching his fifteen-year-old brother have a wank (slow, hard, languid, god) and said brother knows he was there, but that's all. And Reg, though a lot of things—Slytherin being the first one that comes to mind—isn't daft enough to start giving his older brother, who knows a lot of hexes and outweighs him by at least twenty pounds, a hard time. Well. Anyway.

After two days the incident hasn't been mentioned again and Sirius relaxes, certain he was right and that he can just forget the whole wanting insanity.

What happens next, though, reminds Sirius swiftly that one should never underestimate a Slytherin. Particularly if that Slytherin is also a Black, because Blacks want and compete and play fast and loose with the concept of right and wrong.

It's another stupidly hot, humid afternoon, and he heads up to the bedroom to retrieve quill and parchment, intending to write to James and complain about how bored he is.

Flinging the door wide open on its hinges, Sirius steps into the room. Immediately, the white-hot desire flares and explodes around the base of his spine as he registers an almost perfect recreation of the scene he's been trying to forget about.

Reg's not wet this time but his upper lip is shiny with sweat; his chest, face and cock flushed with heat and effort and arousal as he fists his erection and props himself up on the other elbow, looking Sirius right in the eyes. There's a lot to take in but the thing that hits him in the chest with the force of a bludger-strike is the heat in those eyes so like his, the heat he's never seen before and thinks he might never get out of his head.

Hard and exposed and breathless, heart hammering, Sirius holds the eye contact helplessly and licks his lips.

Reg's eyes darken instantly and he comes all over his hand with a long cry of pleasure. Sirius staggers slightly and grabs for the doorframe. Reg blinks at him in slow satisfaction, smirks, and lifts his hand to his mouth. The quick, pink tongue fluttering over that... warm-shiny-sticky-fluid-long-fingers is too much for Sirius and he bolts from the room.

The only thing that stops him from erupting on the spot is some stupid disembodied voice in his head telling him that 'Blacks do not come in their pants from watching their brothers jerk off'.

As Sirius leans against the inside of the bathroom door and releases himself into his hand in three hard pulls, he's starting to think that maybe, actually, they do. And he's not quite sure what he's supposed to do with that.

That night, having successfully avoided Reg for the rest of the day, Sirius once again stubbornly pretends to be asleep, because—and this is possibly a first—he's thinking. He's weighing up the shocking and intriguing idea that this hot, dirty want isn't just his alone, and the thought of giving in to it twists his insides with squirmy hot oh fuck yes. Yes, yes, yes.

Weighing, anyway, weighing that against the fact that in spite of everything he wants to believe, it's probably very, very wrong and very bad to want this. But then that's just a jagged twist of dark pleasure that sharpens the thrill, and that's no good.

And all of this, of course, has to be weighed against the fact that he's essentially being out-manoeuvred by his little brother. Regulus has power over him and that's all wrong. But then again, so is wanting to fuck your sibling through the mattress until he screams, Sirius concedes.

He groans inwardly and buries his face in his pillow.

**~*~**

Unfortunately, the next days only serve to compound his long-held belief that Regulus is, in fact, evil. Reg says nothing, but he doesn't need to because his smouldering glances, the new little hip-sway in his walk, the way he keeps tilting back his head to expose his pale throat and the way he smirks with one corner of his mouth and trails a casual hand over his inner thigh while seated across from Sirius in the drawing room, all coalesce to reduce Sirius to a hot, jittery, aching tangle of need.

It's ridiculous, he tells himself. He can't want it that much. Want him. It's just Regulus.

At the dinner table, their parents argue snippily over some pureblood crap that Sirius barely bothers to comprehend. Reg, whilst calmly eating his potatoes, runs a socked foot up the inside of Sirius' calf. Sirius drops his fork. Looking is one thing, but touching is a whole new game. Sirius' mother reprimands him loudly for the fork-dropping and Reg's eyes flare with heat until Sirius is so hard that he feels like sobbing.

"Sit up straight, Sirius," she snaps. "Blacks do not slouch."

"Yeah, Sirius," Reg adds, still caressing his bare ankle, glossy black hair falling softly over those wicked eyes, laughing silently. "It's not hard, is it?"

Sirius grits his teeth and wonders just how smug Regulus would look getting pounded into the fucking floor. Not that Sirius is going to. And not because it's wrong, even though it is. Dirty and wrong, and actually, knowing Reg, he'd probably manage to look very smug indeed.

When Reg disappears straight after dinner, Sirius knows. He knows exactly what he's doing up there. Sirius sits in the garden for almost an hour as the sun goes down, arms crossed firmly, foot tapping madly out of time with the race of his blood and the throb of his heart.

When he feels as though the longing might just liquefy his insides, he knows that no amount of bathroom wanking can slow its progress, not any more. Unsteadily, he climbs the stairs. Sticky-slippery, the sweat is pouring off him and he knows that he can't attribute it entirely to the stifling heat.

Door open and a double-take—Reg's bed is neat and empty; Sirius' eyes slide to the left, to his bed, and oh, fuck. The small smirk tells him that Reg knows he's there but his eyes are downcast. Sirius needs to see them. Reg's slender body is sweat-slicked all over, glistening, and his movements are shaky, muscles drawn tight as though he's barely hanging onto his control. As if he's been waiting.

"Fuck," Sirius whispers, and blue-grey eyes lift to his immediately.

Regulus pauses, gripping himself tight, and for a moment neither of them breathes. Sirius takes one step into the room, never breaking eye contact, and Reg jerks and spills over his hand, whispering, "Sirius," and shooting hot, white ropes over his stomach.

And it's just his name, but Sirius has always liked his name, and hearing it fall so wantonly, so naturally, from his brother's lips as he loses himself is the hottest thing he's ever heard and Sirius is undone.

He doesn't give a fuck if it's a power-play any more because he's having it. Now. Reg's eyes answer his want with a demand and a plea and it's like looking down at a mirror image of himself from the end of the bed. Almost. Slightly darker eyes, slightly smaller stature, Reg's hair is shorter and straighter, but it's close enough, and Sirius spares a split second to note his own narcissism.

Within seconds, he's out of his clothes and climbing up onto the bed, kneeling between Reg's parted, drawn-up thighs and hesitating just for a moment to stare down at his brother's flushed face. Then he's canting his hips forward and pushing his impossibly hard cock against Reg's flat stomach, sliding it through sweat and slippery, cooling come and groaning out loud as Reg's spent cock gives an interested twitch against his belly.

And there's no doubt in his mind when Reg's hands uncurl from the sheets and come up to dig blunt nails into his buttocks, holding him in place.

"Asking for it, Reg," he mutters, gliding back and forth slowly, utterly owned, claimed by want. And by Regulus.

"I know," Reg pants, pushing up into the grind, lips parted to expose perfect teeth, eyes half-closed and unfocused. "Fuck me. Siri—" His eyes flicker. "—fuck me."

Electrified, spine to cock to centre, Sirius groans. "Yes," he gasps. "Yes."

Pulling back to sit on his heels, he rubs the pad of his thumb in slow circles around Reg's shamelessly exposed twitching hole, watching his cock jump at the touch.

"Stop teasing, for fuck's sake," Reg hisses, grabbing Sirius wrist, fingers wrapping tightly. "In me. Now. I'm ready."

"Thought you liked that," Sirius mumbles to himself, but presses eager fingers inside the tight, slicked passage; they slide easily, and Reg's smug eyebrow-lift as he looks up sets Sirius on fire. He has been waiting.

He drops his eyes to watch his own fingers slide free of Reg's body and grabs his own cock, holding onto his control and knowing, for all his posturing, that he's probably not the one in control here. Or winning, but then he's never been a very good Black anyway.

Staring down, bottom lip between his teeth, he slides inside, watching the gorgeous stretch with a dry whimper. Reg stiffens and spits his name and Sirius no longer cares about any of it, not when his cock is enveloped in Regulus' burning, grasping, tight heat and he can't hide the groan that rips out of his chest.

He closes his eyes and whispers a silent prayer for his soul to no god in particular, then blinks and looks straight into lust-blown, desperate slate-grey Black eyes, digs his fingernails into slim, pale hips and slams his hips forward, burying his cock so deep inside his horribly beautiful, wanton fifteen-year-old brother that he shudders and cries out.

Long legs wrap tight around his back and those nails dig painfully into his arse.

He draws back and slams forward again, consumed, staring down, unable to shake the thought that it's like having sex with a darker, slightly more delicate version of himself, and he's never wanted anything so violently in his entire life. No holding back, and Regulus makes dry, broken sounds with every stroke; Sirius wonders if he's hurting him but can't stop, relieved when Reg grits his teeth and insists:

"Harder."

"Until you scream, Reg," he manages, shifting until he's practically bending his brother double, leaning down to angle harder, deeper, sweat-heavy hair spilling over Reg's face, hot breath against his cheek.

He's close, so close, shrouded in heat, and the warm, wet mouth urging his open is a complete surprise. Sirius almost misses a stroke and his eyes fly wide open, pulling back half an inch from Reg's lips, stomach twisting.

"What are you doing?" The words are mumbled against salty skin as they continue to move together.

"I would have thought that was obvious, Siri."

Sirius doesn't think he's ever rolled his eyes during sex before, and he'd laugh if he didn't feel so close to the orgasm of his fucking life. But he didn't expect Reg to want to kiss him, that's so...

"Wanker," he murmurs, forcing a hand between them to palm Reg's cock. Licking a stripe of damp, brackish skin up the side of his face. Pushing harder, faster.

"Mm."

Reg snorts, pushes back and slides a hand up Sirius' damp back to tangle in his hair, kissing him hard and slipping their tongues together. The sensation is too much and Sirius kisses back messily, gasping into Reg's mouth and emptying himself hotly inside his brother as his flattened, damp palm demands Regulus' release from him.

Sirius can't get his eyes to open, but he does hear that aching cry of his name that just precedes the hot splash over his fingers, and he slides out and back in just one more time for good measure. Reg whimpers and presses his open mouth to Sirius' forehead as he collapses down on top of him.

They slow and cool and breathe together in the silence. Sirius' head spins and he decides he's not moving, ever. It's still ridiculously fucking hot in here, and he has the sneaking suspicion that as soon as he's got his breath back, he's going to want this all over again. Perhaps more desperately, because now he knows how it feels to have something so wrong that it's all the way back around to right, and to give in, and, perhaps, to lose.

To a Slytherin.

Reg wriggles underneath him and tugs lightly at his hair. "Siri, I can't breathe."

Sirius hums and licks him again. "You should've thought of that, shouldn't you?"

There's no reply, but he feels Reg's smirk against his shoulder. And wants it.

-fin-