Sherlock believes in the means to an end. So he doesn't mind at all when John occasionally pulls a gun on a suspect. Death threats are often the easiest ways of getting people to reveal what he needs them to.

And there's something about John when he's holding a gun that's just so…hypnotizing. Surgeon's hands holding the gun steady, confident and solid stance. That delicious little half smile when the other person surrenders, confident and controlling and just so sure…Sherlock swears he's memorized that smile by now, because he keeps thinking of it at the oddest times.

Sherlock loses his train of thought (a rare occurrence, to be sure) when he arrives at 221B Baker Street to find the lights off and everything dark. He starts for the light switch, calling John's name, but that plan is quickly aborted when someone grabs him by the waist and presses a gun to his temple.

"Hush now, and stay still. Wouldn't do to have to shoot a pretty thing like you without any time to play, now would it?"

He knows that voice. Has nightmares about it, on the rare occasions he sleeps.

"Really, Moriarty? Wouldn't a crime as common as rape be beneath you? I'm disappointed."

There's a (surprisingly gentle) nibble to his ear as the man behind him responds.

"Beneath me? No, I'm deliciously sure that that place is meant for you. And don't worry. I'll make sure you never have to leave it."

The gun traces down over Sherlock's cheekbones and across his lips, slowly going back and forth, back and forth. Sherlock resolutely keeps his lips closed, sure that Moriarty, at least, needs one hand to keep him from running and so can't cut off his breath supply.

He gets the sickening feeling of a mistake when he feels cuffs snap closed around his wrists, an experimental tug revealing them to be wrapped through the door handle. He can feel Moriarty in front of him, now. The sickening feeling doubles when Moriarty's fingers pinch his nostrils closed. Sherlock holds out for as long as he can, but is eventually forced to gasp for breath, at which point Moriarty quickly shoves the gun into his mouth. Sherlock feels Moriarty toying with the safety.

"Do you want me to turn this on?"

Sherlock tries to answer around the barrel, but it's too thick and he can't enunciate at all, so despite all his effort, it comes out sounding more like a moan.

"You know, I don't think you do. I think you like it. Like the danger. Like the knowledge that at any moment I could simply twitch, and you'd be dead. Despite your best attempts otherwise, you're getting hard. Right. Now."

He palms the bulge in Sherlock's trousers, gaining what is definitely a shameful groan from around the barrel of the gun. He starts up a steady rhythm of strokes, waiting until Sherlock's eyes are closed and he's starting to make what sounds suspiciously like 'please' around the gun before stopping and putting his now-free hand on Sherlock's shoulder.

"Suck."

Sherlock's so far gone at this point that he just obeys, hollowing his lips around the metal in his mouth.

"That's a good boy, you look so pretty like that, hard and aching with something in your mouth and no way to get yourself off."

And although it would truly be a feat only Moriarty could manage, getting bored with that sight in front of him, well, Moriarty manages.

He pulls the gun away from Sherlock, grinning as the barest hint of a whimper escapes Sherlock's gorgeous lips. He returns the gun back to its previous place against Sherlock's temple.

"Now darling, our options are getting rather…constrained if we stay here. I'm going to uncuff you, and you won't try to run."

It's not a question, but Sherlock nods anyway.

"Good boy."

Moriarty leads Sherlock to his bedroom and locks the door behind them before sitting on the bed, looking for all the world like he owns the place.

"Now then. I think you owe me a thank you for deciding to come play with you, don't you agree? Undress."

For a second, Sherlock looks like he's going to refuse. Blisteringly fast Moriarty is at his side with the gun again, running it over Sherlock's face and down his neck before using it to push up his chin, watching his Adam's apple bob.

Sherlock was pretty sure this shouldn't have been turning him on the way it was, but the feel of cool metal, still slick with his own saliva and the feeling of danger and just everything is putting him into a state of complete overload and—

Moriarty bites down, hard, on Sherlock's pulse point, and is rewarded when the taller man sags against him with a moan.

"Ready to cooperate? "

Sherlock manages a weak nod, and Moriarty smirks against his neck and steps away again.

"Good."

Slowly Sherlock begins to unbutton his shirt, his eyes sliding closed.

"Uh uh uh," Moriarty sing-songs "Look at me Sherlock. I want you to remember exactly who you're with. Who's making you feel this way. Who will…own you."

Sherlock feels himself tremble a little bit at those words, and, unbidden, his hands start working his clothes off faster. Soon he finds himself completely naked in front of Moriarty, shuddering as the other man's gaze blatantly sweeps up and down his body.

"Now then, how about the rest of that thank you? I want to know just how glad you are I came, pet."

Moriarty returns to the bed and points Sherlock to the ground in front of him. Sherlock slides gracefully to his knees and starts nuzzling his face against Moriarty's crotch. Moriarty sighs and tangles his hand in Sherlock's hair, resting it in his curls for a few moments before yanking him up by it so that his eyes are on Moriarty once more.

"You are going to worship my cock, because I have decided to visit you tonight instead of any of my other…acquaintances. Do a good job, and I might even decide to come back."

He releases Sherlock, who pulls down Moriarty's zip and is startled to see a distinct lack of pants. Sherlock moves to undo the button and pull Moriarty's trousers down, but is stopped by another harsh tug to his hair.

"That's enough pet. After all, if you're as enthusiastic as you should be, all that really matters is my cock, hmmm?"

Sherlock obeys and wraps his mouth around Moriarty's hardness, grinning as he hears the man above him moan. He begins to bob his head, taking Moriarty in as far as he can go and sucking hard before backing off to breathe through his nose, massaging with his tongue.

"Oh I swear…nnngh…you were…mmm…born to do this. Fuck."

All too soon Moriarty has to pull Sherlock away, lest playtime be over too soon. Sherlock makes the most intoxicating little disappointed noises, which quickly turn into a groan as Moriarty stands and goes back to the bruise he left on Sherlock's neck earlier, licking and sucking the already marked skin.

"On the bed, on your stomach, spread eagled."

Sherlock does as he is told without complaint, yelping a little bit when he feels cold metal running across his back—the gun—and Moriarty straddle his legs.

"Now then darling, just stay still so we can get this over quickly and move on to more…entertaining things."

Sherlock's so focused on the feel of the gun that he doesn't really register Moriarty preparing him until-oh dear god.

Moriarty grins and rubs up against the spot again, reveling in the shivers of his new pet. Judging Sherlock to be ready, he pulls his fingers away, chuckling as Sherlock mewls and tries to follow them back with his hips.

"So eager, aren't you, my pretty little toy?"

Sherlock moans in assent, arching towards the barrel of the gun as it's slowly dragged down his body.

"I could fuck you with this, you know. You'd let me. Then again, you're so far gone I could do just about anything and you'd beg for more. But should I? No, I think I'll save that for a treat sometime you're very, very good."

Sherlock feels more than hears the gun thunk down on the bed beside him. And it's about this time that his brain registers the fact that Moriarty is still fully clothed, but is preparing to fuck him. Moriarty must have seen the quizzical look on his face, because an answer is forthcoming.

"Seeing me naked is a privilege you have to earn, pet."

He doesn't wait for a response, thrusting into Sherlock in one smooth motion. Moriarty, quite uncharacteristically, waits for Sherlock to relax before proceeding, gently stroking his back.

When he starts thrusting, Sherlock starts up a litany of moans and whimpers, obviously already on edge. But so is Moriarty. The knowledge that he is going to own the one man in the world that is his intellectual equal and the knowledge that they'll still be matching wits and trying to kill each other but Sherlock will come whenever he calls…well, that's one glorious mindfuck right there.

Moriarty feels his phone go off and checks it with one hand, speeding up his thrusts in response to the message.

"Well pet, I'd hoped this could last a little longer, but apparently the good doctor is on his way home, and it really wouldn't do for him to walk in on us like this. Yet, anyway."

He starts stroking Sherlock's cock in rythym, biting at his shoulders.

"Come."

Sherlock once again (and this must be a record number of times in a row, really) does as he is told, and the clenching of his inner muscles around Moriarty brings him to his own climax. He pulls out, wiping his cock against Sherlock's sheets, and tucks himself back into his trousers.

"I suggest getting cleaned up before your little sidekick arrives home."

The rest of the evening is relatively normal, until Sherlock is curled up on the couch after John has gone to bed and his phone vibrates.

Prepare yourself every morning. Who knows when I'm going to visit, and Daddy doesn't like to be kept waiting. Goodnight pet. You'll be dreaming of me tonight.

Sherlock shudders and puts the phone away, trying to deny it.

But that night, he dreams of Moriarty.