Title: The Lion's Share
Author: pauraque
Pairing: Regulus/Sirius
Rating: NC-17
Kinks/Themes Chosen: Happy birthday, DD!
Other Content: Teen sexuality, masturbation, sibling incest fantasy, het fantasy
Word Count: ~1400
Summary: Regulus knows he's not allowed in his brother's room, but something keeps him coming back.
Author's Notes: Loosely based on osmalic's art piece A Good Big Brother Always Shares. Thanks to my beta _hannelore!



A Muggle car hisses past in the wet street outside, covering the sound of Regulus clicking open his brother's bedroom door. Sirius is out tonight, and their parents are asleep, but Regulus is still intensely cautious, every nerve standing on end. He pushes the door open painfully slowly, afraid to let it creak, and steps into the only room in the house that is forbidden to him.

The single, tall window is open, and the full moon casts just enough grey light to see by; Regulus doesn't dare cast a spell to illuminate the room any further. The rainy summer breeze rustles through the dark curtains, making the air in this room different from anywhere else in the house — clean and cool. Their father never wants the windows open. It lets in the street smell, he says.

Another car passes, its headlights sliding slowly through the window and reflecting off the pictures on the walls: the gleaming chrome of motorbikes, girls' bright white smiles, and Sirius's school friends laughing in red and gold.

The car sighs away into the darkness. Eyes adjusting once more, Regulus moves forward, placing each foot with care among Sirius's socks and pants on the floor. Regulus's gaze flits over the pictures. Many of them are torn in places where their father tried vainly to rip them down, stymied by Sirius's skill with sticking charms. In the half-light, Gryffindor colours are muted to burgundy and grey.

When Regulus's eyes fall on the girl, he stops.

It's a Muggle. Her blonde hair is feathered about her face, which is slightly downturned and coyly smiling. She is leaning forward — motionless, of course — and her breasts are only half covered by the top of her strapless bathing suit, showing deep cleavage in between. Her stillness is eerie, like the victim of a petrification charm. Regulus peers into her eyes, and they gaze back emptily, doll-like.

Regulus takes a careful step backward and lowers himself down to sit on the edge of Sirius's bed. This is where Sirius sits, just here, looking at the image of this girl. This is where Sirius puts his body, how the mattress yields beneath his weight, how the rug rubs against his bare feet. Deep in Regulus's pelvis, a muscle twitches and tightens.

Looking up at the poster, Regulus's eyes retrace the path of Sirius's gaze, caressing the soft lines of the girl's breasts. He thinks of Sirius imagining what it would be like to touch the wet, exotic fabric of a Muggle bathing suit. Pulling down the front of it and revealing her soft, pale breasts and pink, hard nipples.

At thirteen, Regulus knows about wanking, and he knows his brother does it. Regulus's bedroom is just on the other side of the wall, and he's heard the bed creaking late at night, more than just the sound of rolling over in sleep. If he listens hard enough, he can hear faint snatches of his brother's rough breathing, so riveting that he finds himself staying up half the night listening for it, until he can't tell anymore whether it's real or just his strained imagination.

Regulus presses his palm against the front of his trousers, his toes curling against the rug. When Sirius's bed creaks, he's touching. Regulus knows it. That's why he has pictures of half-dressed girls on the walls, and why Father reduced himself to clawing with his fingernails just to try to take them down. The bathing suit girl's curvy body and secret smile are what get Sirius going, what makes him get the urges that Regulus has only just started to feel as real needs. The smaller, ordinary pictures of Sirius's friends wave in cheerful silence as Regulus rubs himself, lower lip bitten, face tense and pale in the moonlight as he gazes up at Sirius's Muggle idol. Sirius's prick gets hard like this, and it feels like this to him, pressing against the fabric of his trousers.

Regulus has seen his brother's prick before. Sirius was in here, dressing, and the door was half-open, and Regulus didn't know he hadn't got his clothes on yet. He touched the door further open, and Sirius turned, his face open in surprise. Regulus couldn't have seen it for more than a second before surprise turned back to hard anger (Get out of it!) and the door slammed in his face. But it had only taken that long for the image of his brother's prick to be burnt into Regulus's memory, longer and wider than Regulus would have thought, hanging softly below black curls, in front of dark bollocks, and swaying slightly when Sirius moved.

Regulus fumbles open his trousers and touches himself, bare. His prick is hot against his palm and his palm is cool against his prick; he sucks in a breath through his teeth. Lately he's grown big enough to wrap his hand round himself, but he still wanks the way he first learnt to, humping his hips and rubbing against his flat hand.

Sirius is bigger, though. Big enough to do it properly. He sees his brother sitting here, just here on this bed, gazing up hungrily at the doll-eyed girl and wrapping his hand round his thick cock, pumping up and down like Regulus saw in the dirty magazine a boy at school once passed around.

The damp air from the open window passes over Regulus's face and he shivers, grinding his bum into his brother's mattress as he rubs. He imagines these feelings coursing through his brother's body — Sirius alone and pleasuring himself in private, allowing himself to get lost in it. The cruel, ever-mocking sneer uncurls, and he's not the same boy who knocks into Regulus in the hallway and laughs, who used to hold him down and tickle him when he was too little to fight back. When Sirius pores over the poster girl's hourglass curves, he's not like that at all. He is someone softer, more vulnerable. Beautiful grey eyes dilating. A brother Regulus could love.

The bed creaks beneath Regulus's rhythmic bouncing as he searches the model's vacant eyes, desperately wishing he could see what she has seen, know what she knows as she bears silent witness to Sirius's pleasure. Does he imagine this girl real and in his arms? Does he imagine the mystery between her legs, dark and unfathomable? Sirius is getting older, and one day he'll do it. One day he'll bring a girl home late at night, sneaking and snickering past bedroom doors, and he'll do it right here on this bed, with Regulus just on the other side of the wall.

A trembling whine sounds at the back of Regulus's throat as he thinks of his brother losing his virginity, of hearing his brother's moans entwining with the breathy giggles of a pretty girl. He sees himself pressing his ear against the cold wall between them, straining to decode the meaning of every creak, every bump, every whisper.

Regulus is no longer worrying about being heard, nor about what will happen if he spurts come on his brother's bedroom floor. He writhes hard against his hand, panting in short breaths, beneath the beatific light of the poster girl's sweet, unchanging smile. When a car parks briefly across the street, he does not notice it, nor consider the significance. He does not hear the front door open and shut, and a minute later he does not hear the thieflike footfalls on the hallway carpet, until the door flies open with a bang.

The shot of adrenaline almost makes Regulus come, convulsively grabbing his prick as he jerks back in shock, letting out a strangled cry. Seeing Sirius in the doorway, his vision seems to bend, unwilling to see the truth. To see his brother in the flesh, not fantasy, tall and menacing and bigger than Regulus. Frozen in place like the poster girl, Regulus can't even put his cock away, seized by some play-dead instinct from deep in the animal part of his brain.

The headlights of a passing car strike a shaft across Sirius's chest. A moment later his face is illuminated, revealing a hard, heartless smile. As the light crests and slides away, his features briefly turn bright white, with stark shadows beneath his lips and his eyes, and then he is in darkness again.

"Well, well, well," Sirius says, his voice silken and dangerous. "What do we have here?"