Kristmas Wish Fulfilled for: ariadneelda
From: sabethea

Title: Idle Threat
Characters/Pairings: Sirius/Regulus, Severus/Sirius/Regulus
Rating: NC17
Kinks/Themes Included: Angry sex, dub-which-is-more-like-non-con, angst, darkness
Other Warnings: incest (obviously), humiliation
Word Count: ~4400
Summary/Description: Severus finds Sirius and Regulus doing something brothers should not be doing, and exacts payment for his silence.
Author's Notes: Many thanks to my beta, who did her usual great job. Giftee – I hope you meant it about dark, because... yeah.


It is not the first time Severus has seen Regulus sneaking out of the Slytherin common room at a time he should, by rights, have been taking himself to bed. It is not the first time that he has wondered where the younger boy is going; however, it will be the last. Severus is, after all, a Prefect: if Regulus is breaking Hogwarts rules, it is only right that his House Prefect should discover in what ways, and why, he is doing so. Severus counts to thirty, giving Regulus time to get a little in front, and then follows.

The dark, silent room which Regulus enters is not a surprise, and Severus is not naive enough to wonder for what purpose Regulus has gone there: midnight trysting is hardly a rarity in a school full of adolescents. Inter-House relationships, though rarer with Slytherins than the other Houses (Slytherins prefer their own kind, all in all) is also not unknown. Hearing the sound of footsteps, Severus slides back into the shadows, and waits.

A boy, black haired and broad shouldered, passes within a foot of Severus without noticing him. Severus bites back the gasp which might have given him away: Regulus's trysting partner is Sirius Black – Severus's enemy and Regulus's brother. Perhaps the nature of the meeting is not the usual kind.

Sirius, arrogant in rule-breaking as always, flips a side light on as he walks into the classroom. Severus thinks about how much he loathes Black's confidence that rules are made for other people, lesser people than himself. Severus slips to the door again, the intent to remain unseen warring with a desperation to know what the brothers are doing meeting secretly at night. Sirius hitches himself onto a desk, gives his younger sibling a smile.

“So, little bro...” His voice is full of drawling self-assurance, as always. “What has our esteemed mother got to say for herself this time?”

Regulus pulls a letter out of the pocket of his robes, passing it from hand to hand nervously. “Sirius...”

“Oh dear, has her golden boy disappointed her? Are you in Walburga's bad books for conspiring with the enemy, her eldest son?”

Regulus bites his lips, nods. Severus's need to see what is going on has made him take a risk: if either boy were to turn towards the door now, they would surely see him.

“Rumour has it she's burnt me off the family tree,” Sirius says lazily. “I don't think I can bear the shame.”

“Don't you... don't you miss the family?” Regulus offers, his voice shaky.

“Miss them?” Sirius laughs. “Miss the poisonous filth they spread about pure-blood supremacy, the disdain with which they look down on anyone who's not from the Noble and Ancient House of Black? There's not a person in our family” - his voice has hardened now, no longer amused - “that I would ever miss.”

“She says if I keep on terms with you, she'll disown me.” Regulus's voice becomes shakier with each sentence he speaks.

“That sounds like our loving mother,” Sirius agrees. “So what's it to be, Reggie boy? Outlawed with your renegade bro, or continue in the role of golden boy of the family?”

“Sirius, you know – you know I can't...”

Reg looks on the point of tears. Not for the first time, Severus wonders what it is about the older Black which inspires such devotion: given the chance of losing Sirius from his family, he would be more than grateful.

“No.” The monosyllable lies between the two brothers like a barrier, and to Severus's surprise it is Sirius who makes the move to remove it. “No,” he says again, but more gently. He slides off the desk. “Did I say that there was no one in the family who I would miss?” he asks, moving over to Regulus. “I lied. There's one person I will, Reg.” Sirius's hand is on Regulus's cheek; he turns his brother's face up towards his own and drops a quick kiss on Reg's lips. “If I'd do it for anyone, little bro, I'd do it for you. But I can't.”

Severus can't see for certain, but he thinks that Regulus's threatened tears are falling; he can't repress a disgusted sneer at the thought of crying over Sirius Black.

“Can't you?” Reg asks, leaning his head against Sirius's shoulder.

“Merlin, if I could...” Sirius's tone has changed; it is deeper, huskier. Severus watches as he pulls Regulus close in to him, almost violently. “For you, Reg...”

And Sirius's mouth is on Regulus's, in a kiss that no one could call brotherly; a kiss so passionate that even watching it makes Severus grow hard, makes him rub a hand over the robes cloaking his erection. Regulus's arms are around Sirius, and there is equal heat in his response; Sirius breaks away with a groan, his mouth nipping at Reg's neck, his hands firm on his brother's arse as they rub against each other. And it is hot, hot to watch, and Severus's hand clutches at his cock – and it is wrong, and disgusting and... and because of that Sirius is utterly, totally in Severus's power, and this is not a moment to waste by bringing himself off as he watches them. Severus has got Black exactly where he's always wanted him. Sirius is pulling Regulus's robe from him with rough, desperate hands, pushing his pants down to hold his brother's erection in his hand.

“Merlin, Reg...”

“Sirius, please...”

Severus is in the room with them now, and neither has noticed, so engrossed in each other as they are. Brother on brother – it is sick, perverted... and unbelievably arousing. For a couple of minutes, Severus is unable to do anything but watch, his breathing almost as unsteady as the brothers', which is all the time it takes for the two boys to be naked, Regulus perched on a desk with his legs as well as his arms around Sirius, their cocks rubbing up against one another's. But now, now they have opened themselves to discovery - to blackmail (and Severus is amused by the appropriateness of the term): there is no way on this earth or out of it that they could claim a strictly brotherly interaction in this embrace.


“You are out of bounds, Regulus Black,” he says quietly, a faint smile on his lips.

The boys leap apart; Sirius reaching instinctively for his wand – which is out of reach, discarded with his clothes.

“What the fuck...?”

“Well, well, well,” Severus says maliciously. “Sirius Black – so desperate, he'd fuck his own brother. Apart from the minor matter of breaking bounds, there's a few more significant rules being broken here. Such as, for example, incest... not to mention sex with an underage wizard. You could be in a lot of trouble, Black, if I were to mention this to anyone, wouldn't you?”

“Don't you fucking dare.” Sirius advances on Severus; Severus almost admires the arrogance which makes a naked, unarmed boy think he can threaten someone holding a wand and all the cards in the pack.

“I really don't see how you can stop me,” Severus says coolly. Regulus, in the background, has fumbled his way back into his robes, Severus notes. That's fine by him. It will be all the more enjoyable undressing him later. “You could always try asking nicely, Black. You never know – I might be feeling generous.”

Sirius swears softly, a fluent litany of bad language. Severus waits for him to finish, the smirk not fading from his lips. He sees Regulus try to slip round him and away and swiftly reaches out a hand to hold the younger boy's robes and prevent his escape.

“I haven't finished with you, Regulus Black,” he says. His eyes flick back to Sirius. “I haven't finished with either of you.”

Regulus looks close to petrified; Sirius, Severus notices with pleasure, is beginning to realise just how much trouble he's in. Engaging in sexual activity with an underage boy would do damage enough, both to Sirius's reputation with the authorities and even more so with the girls who so often hung around him adoringly. When the boy is a brother, however... Sirius is looking at best at expulsion and utter humiliation; at worst at being tried by the Wizengamot.

“What do you want?” Sirius asks, making a clearly painful effort to keep his voice level, unthreatening.

This is perhaps the most enjoyable moment of Severus's life, and he intends to exploit it to the full. “Are you going to beg me not to tell?” he asks smoothly.

“Please.” The word comes from Sirius's lips with difficulty.

Severus's smile grows. “I said 'beg', Black. On your knees.”

Sirius looks for a second as if he is frozen to the spot. He is shaking, Severus notices without sympathy. He glances towards his brother, whose white face contrasts sharply with his black robes. Sirius himself is still naked, and he hasn't even thought to protect his modesty. Things have gone too far for that to be an issue. Regulus is casting a pleading look at him, and Sirius, his hands balled into fists, is nonetheless dropping to the floor. Kneeling in front of Severus Snape, the boy he has humiliated time beyond time.

“Please,” he says again. “Not for me, for Reg.” He can't meet Severus's eyes any more; is looking at the floor. “He doesn't deserve this.”

“Such brotherly devotion,” Severus drawls ironically. “Or should that be – very unbrotherly devotion?”

“Fuck, Sni... Snape, don't do this. You can do what the fuck you want with me, but Regulus is a kid, okay? You can't fuck up his life just for one stupid moment.”

Severus raises an eyebrow. “Interesting. So in your own words, you've been having sex with a child? And you think that's something I ought to keep silent about? Would it really be fair to let a child molester get away with his crimes scot free?”

“You bastard.”

Sirius looks like he's about to puke. Severus wonders whether he's seen such a beautiful sight before: Sirius, on his knees, nude, on the point of falling apart in front of his despised enemy's eyes. He pushes Regulus back towards his brother.

“Kiss him again, Black.”

“What?” Sirius is taken by surprise, looks straight up at Severus at last.

Severus leans back against a desk. “You heard. Kiss him again.”

“You're mad,” Sirius breathes.

“Oh no, definitely not. You can get up from the floor, even, to do so. I'm feeling kind.” Severus's tone is polite but determined; he knows Sirius will understand that he is serious.

“S-Severus...” And it is the first thing Regulus has said since they were discovered. Up until that point it had been a battle of wills between two acknowledged enemies. Regulus was merely a pawn in the game.

Severus reaches a hand out to stroke Regulus's arm; watches Sirius twitch as he does so. “Not if you don't want him to, Regulus,” he reassures the younger boy. “If he's been touching you against your will, I'm quite prepared to report him to the authorities. I'm your House Prefect, after all – it's my job to protect you from abuse such as you've undergone tonight.”

Severus is aware of Sirius's every motion, knows that his enemy is equally aware of the trap which has been set. The choice is cruelly simple: do as Severus says, or be reported. And even arrogant Sirius Black will not risk being reported in this particular situation.

“I – I didn't...” Regulus stammers.

“Oh, you did,” Severus says. “I saw, remember?” He looks down at Sirius. “Kiss him again, Black.”

Sirius rises shakily to his feet, motions his brother across and gives him a brief peck of a kiss.

“No, no,” chides Severus. “Kiss him as you did before. Show me how much you love your brother.”

“You're sick.”

“And you,” Severus says, “are not in a position to argue, now are you, Black?”

“Sirius...” Reg pleads. “Sirius, we have to. I – I can't...”

Mentally, Severus blesses Regulus. Sirius Black might have risked it all, have challenged Severus to do his worst. But he will not reject his brother's plea.

“Yeah.” Sirius breathes deeply. “I'll see you through, Reggie. I promise.”

And oh, Severus is going to enjoy holding Sirius to that particular promise. He watches as Sirius pulls his brother close and presses his lips against his. Even with Severus watching, Reg cannot help but submit to such an embrace; he snuggles closer to Sirius.

“Very nice,” Severus says. “Now, Regulus, come here and show me how your brother kisses you.”

Sirius takes a step forward, pushing himself between Regulus and Severus. “You're not touching him,” he snarls.

“Jealous?” Severus can smile at Sirius's fury, so impotent as it is.

“I'll kill you.” Sirius's teeth are bared; he is animalistic in his anger. “I swear it, I'll kill you.”

“Come here, Regulus,” Severus says, ignoring Sirius. And Regulus, as if possessed, moves slowly towards his Prefect. “Good boy,” says Severus kindly. “Now...” He reaches out to pull Regulus close. “Show me.”

Regulus is submissive, waiting for Severus to make the first move. Over his shoulder, Severus can see Sirius becoming ever more aware of his own powerlessness. Severus kisses Regulus chastely, waiting for Regulus's response before deepening the kiss, strengthening it to the point where Regulus leans into him, dependent on Severus to keep them both upright. It is Severus who pulls away, Severus who is in control of everything. He puts Reg to one side with surprisingly gentle hands, then says:

“And now, Black,” (they might both be Blacks, but only one of them is 'Black' to him,) “I want to feel what it means to you. Show me how you kiss your child-brother.”

Sirius's anger seems to have passed the boiling point. There is still murder in his eyes, but he knows too well that he has no choice. Coming up to Snape, he stares straight at his face for ten full seconds, his mouth curling with disgust, before he obeys. The kiss is passionate but angry; Severus knows for sure that Sirius doesn't kiss Reg just like this, but there is heat and rampant sexuality in Sirius, which forces itself out. Once again, Severus is growing hard, but this time he wants more than just kissing.

“Okay?” demands Sirius, pulling himself away.

Severus shrugs. “As far as it goes.”

“Fuck you,” Sirius swears.

Severus laughs aloud. “You might be prepared to fuck your brother, Black, but if anyone else is going to be fucked tonight, it's you.” He watches Sirius's expression change; sees a bead of sweat roll across his forehead. “What, are you turned coward?” he taunts.

Sirius takes several unsteady breaths. “And... if I do as you ask?” The reluctance in his voice is tangible; it is equally clear, however, that he's prepared to submit, no matter the personal cost, if it will save Regulus.

“If you both do as I ask,” Severus corrects.

“I've told you before – leave him out of this.”

“And I have told you before,” Severus responds, “that you are really not in a position to argue. Or are you? Are you prepared to be exposed as the pervert you truly are?”

“He's not!” Regulus's face is suffused with red as Severus turns to look at him. Reg looks down, away, anywhere but at either Severus or Sirius.

“Reg,” says Sirius quietly.

It is enough. Regulus will do as Sirius says and Sirius knows he has no choice but to do as Severus tells him. Severus has them both precisely where he wants them – neck deep in shit, with him the only person who can pull them out or let them sink.

“I could fuck your brother,” Severus says, conversationally, to Sirius. “I could fuck him as he sucks your cock – how about that? He could do us both at once.”

Sirius shakes his head slightly. His eyes meet Severus's, and Severus thinks he has never seen Black so terrified. He is pleading for mercy, and Severus could get hard on this moment for the rest of his life.

“Oh,” Severus says, unable to resist, “do you not want to share?”

“For pity's sake,” Sirius starts; but he cannot finish. There are all too many reasons why he can't beg pity from Severus Snape. He looks away. “Whatever you want,” he says dully, “if you won't tell.”

Severus pulls Regulus round in front of him, looking him up and down. Regulus's eyes are cast down.

“He's a pretty kid,” Severus says to Sirius, over the boy's shoulder.

Sirius says nothing, and Severus begins to undo the buttons on Regulus's robes. Reg is standing there, motionless, allowing Severus to do what he will.

“Don't,” says Sirius sharply, adding, reluctantly, “please.”

Severus ignores him, finishing the unbuttoning and pushing Regulus's robes to the floor. His pants follow, until Severus is the only dressed person in the room; Regulus is as naked as when Severus first interrupted the brothers.

“Very pretty,” says Severus dispassionately, running his hands all over Reg's body.

Sirius takes a step forward, then stops, hamstrung by his own powerlessness. “Snape, please...”

“Are you going to enjoy watching me fuck your baby brother?”

“You can't – you won't do this.” Sirius sounds ever more desperate; it is beautiful.

“Persuade me.”

“I'll do anything.” Sirius is shaking and sweating at the same time.

Severus runs a hand over Regulus once more. “You fuck him.”

The loudest silence Severus has ever heard fills the room. Sirius's eyes meet Severus's, and they stare at each other for a long, long, moment.

“You don't mean that,” Sirius whispers.

Severus shrugs. “Your choice. I can do it or you can do it.” He smiles. “Do you think I could make him scream?”

“I thought you were going to fuck me,” Sirius says – and he is actually begging Severus to do so, for Severus to stick his cock into Sirius's arse and pound him into the ground.

“I was,” says Severus, “but this seems a better idea. I'm very generous, I think. You know, and I know, that you want to fuck him. I'm giving you your heart's desire.” He pushes Regulus towards Sirius; Reg stumbles, and instinctively his older brother puts a hand out to steady him, to prevent him falling. “Very touching,” Severus says drily.

“Sirius,” Regulus whispers, pleadingly; the one thing Sirius cannot ignore.

Sirius's hand is still on Regulus's arm from when he stopped him from slipping over. “Yes,” he says quietly – a promise. He looks back to Severus. “Is there anything - anything I can offer you?” he entreats. “You want me out of Hogwarts? I'll go now if you ask me. I'll get myself expelled if that's what you want.”

“Hardly a big sacrifice considering I can make certain you're thrown out.”

“Leave Reg out of it, though. For God's sake, he's a Slytherin – he's one of you. You can't fuck up his life because you hate me.”

“But it makes it so perfect,” Severus explains. “You'll be far worse hurt this way than any other. Now, are you going to do what I tell you or not?”

Sirius looks at Regulus, a long hard stare which seems to give him the determination to do what he must. “If I do, you won't tell?” he says again.

Severus gives a wry smile. “Persuade me,” he says again.

Sirius's concentration is still on Regulus. “Forget this,” he says insistently to his brother. “Forget everything tonight. I am not your brother, I'm cursed from the family. Remember that.”

“Yes.” It is not even a spoken answer from Reg; his lips frame the word.

“So,” says Severus blandly, “are you going to do him or am I?”

Regulus shrinks a step nearer to his brother; the inference is obvious.

“I am,” Sirius says, then makes no move further. Severus raises an eyebrow, and Sirius takes a deep breath. “I... need a wand,” he says.

“And it is so likely, Black, that I'm going to give you one,” Severus retorts.

Sirius looks at Regulus, looks back at Severus. “No,” he says, “I really... I can't...”

He can't get the words out, but suddenly Severus realises what he means. “Allow me,” he says, ironically. The spell is cast, lubricating Sirius's flaccid cock and Regulus's arse. “Better?”

Regulus has turned towards his brother, buried his head against his shoulder. It is all so familiar – just as they had done when they were alone, except now... now Sirius's response is not going to be consoling so much as increasing the misery. Part of Severus feels that he ought to feel sorry for Reg, but – well, Regulus has never shown him any sympathy, and his love for his brother is enough to make Severus feel he deserves what he gets. Severus clears his throat. Sirius murmurs something that he can't hear into Reg's ear; Regulus's arms close tighter around his brother for a second before he lets go.

“Over the desk,” Severus instructs.

“Fuck's sake, can't you just...” Sirius catches Severus's eye and shuts up. It is amazing what a turn on power can be. Sirius is looking helplessly at his soft member. “Look, I can't...”

Severus gives a half-smile. “Get him to suck it for you,” he suggests.

“I will kill you.” Sirius's tone is not threatening now, not even angry. It is the voice of despair, of a boy who doesn't even believe his own words.

“But not until you've fucked your brother,” Severus says.

“Reg...” Sirius has turned his back on Severus, is reaching out to his sibling. “Come here,” he says. He holds Regulus close. “This is not happening, Reg. I'm a stranger, I'm a rapist, I'm whatever you want. This is not your fault – none of this is your fault.”

Severus smiles sardonically; it seems Black really does love his brother. Perhaps it will be good for him to discover how it feels to lose someone you love. So many years of everyone falling at his feet. It's not so comfortable to be falling at someone else's, is it, Black? Sirius looks back over his shoulder at Severus, clearly hoping that his enemy will relent; the expression on Severus's face makes it obvious that he will do no such thing.

“Over the desk, Black,” he says again. “Over this desk.” He gestures to one in front of him; one where he will be able to see the faces of both Black brothers, and enjoy every moment of his supremacy.

“I love you,” Sirius whispers to his brother, as gently he pushes Regulus down across the desk. “I love you.”

Sirius's hands are all over Regulus; it seems as if he is drawing strength from his touch on Reg's body. He does not look up at Severus at any point, concentrating all his attention on his sibling. His cock has become half-hard, even from this contact with Regulus, and he reaches a hand between his legs to fondle it harder.

“Want me to do that, Black?” Severus asks mockingly. He has shrugged aside his own robes, touching himself in unison with Sirius.

Sirius doesn't answer. Severus wonders whether those truly are tears in his eyes, and if so, whether life can get any better than this. Sirius has closed his eyes as he touches himself – trying to pretend, no doubt, that Severus isn't there. But Sirius knows as well as Severus that this is something he can't forget. Apparently, though, Regulus is enough of a turn on; Sirius's cock is standing to attention once more, and he has dipped one – two – fingers inside his brother, stretching him gently so that his arse can hold a cock – can hold Sirius's cock. Regulus is looking down at the desk, as if attempting to memorise every scratch it holds. Yet despite everything, he too is hard, moaning quietly at the feel of Sirius's fingers inside him.

“Beg him for more,” Severus says to Regulus, his hand stilling on his cock for a second.

For a second, Regulus's eyes flick upwards to Severus's face. He looks down again, muttering, “Sirius” - the name undeniably some kind of plea.

“Yes,” soothes Sirius; and he pushes into his brother.

Regulus arches his back, groaning again at the feeling. Sirius opens his eyes and keeps them fixed, accusingly, on Severus. As he pumps in and out of Reg, Severus keeping exact time with him as he wanks, his eyes never stir from Severus's face – not even at the moment when, with Sirius's hand on him, Regulus comes messily all over the desk; not even as he himself gasps as his cock throbs and twitches inside his brother. Severus comes too: he has been standing so close to the pair that his come sprays across the desk, some of it splashing Regulus's face.

Severus has turned away almost before the boys have come down from the orgasmic high. But as he gets to the door he hears Sirius once more.

“I'll get you for this, Snivellus. I'll get you.”

He smiles. Six months later, saved from a gruesome death only by James Potter's quick reactions, he discovers that it was not an idle threat.