This is pure, unadulterated smut. I regret nothing. I also really like italics. Like, a lot.

I wrote this in maybe thirty minutes, and I should really be asleep right now but when the calling for some good ole' McCoy/Chekov lovin' comes knocking, you just don't turn that down. You just don't.

Edit: I've run back through it and edited bits and changed some stuff around now that I've had some sleep. So maybe it's a touch better now.

Warnings: SEX. GAY SEX. LOT'S OF IT. IN DETAIL. Also language. You have been sufficiently warned.

-:-

It took approximately three seconds for Leonard McCoy to decide that the boy's mouth should be fucking illegal.

Chekov had seduced himself into McCoy's bed – or rather, between his knees – in record time – about two bats of his eyelashes, a mumured please followed by it's Russian counterpart, and a well-timed enlarging of his already-far-too-big blue eyes. It really wasn't fair.

But McCoy was a doctor, not a god damn saint. Those lips practically begged to have a cock placed between them, and the doctor would be lying if he said he hadn't thought about doing just that. Often. Probably too often.

And now those wide, pink lips were stretched around his thick cock and god damn his tongue was flickering and fluttering and laving all over him like he was an honest-to-god lollipop. He could be fucking grape flavoured for all the enthusiasm Chekov was applying to his dick.

Oh, God – the ensign had just swallowed him whole, working his throat around the cock in his mouth and he was humming like he was right at home between McCoy's thighs, sucking his soul out through his dick.

Maybe he was.

And really, McCoy would let him suck out his soul and then some if he just kept doing that fucking yes right there

Chekov pulled off his cock, raising his eyes to meet Leonard's, and he was practically glowing with content. McCoy thought an eighteen-year-old ensign really shouldn't look so fucking right between a man's thighs, much less his, but he really did, and fuck if McCoy didn't want to see him there again, or maybe on the bed as he plunged into that gorgeous, lean body –

"Is good, Doctor? I am pleasing you?" His voice was thick, throaty. Sucking cock probably did that to you, McCoy mused.

"Fucking hell, kid, it's more than good. You don't even have to ask."

"Pavel," the boy licked the underside of his cock, then tongued the precome off the tip. "My name is Pavel."

"Pavel, yes, fuck yes," McCoy breathed, and he sounded so helpless but he really was at that moment, and he couldn't find it in himself to give a fuck.

"You are wanting to fuck me now, da?" Pavel murmured, and McCoy's fingers clenched in that curly blond hair. Things like that should never come out of Pavel Chekov's mouth without a big fat warning to prepare people, because he really felt like damning all caution and coming all over the boy's angelic face.

"Yeah, Pavel. I'm wanting to fuck you now," he growled, and Pavel grinned like Tom when he caught Jerry in those old-ass cartoons before crawling onto the bed and arranging his long limbs around until he was lying on his back, spread open and ready for Leonard's use.

It was art splayed out on his bed and McCoy suddenly never wanted Pavel to be anywhere else but right there, on his bed, waiting for the pounding of his life.

"Damnit, Pavel, you're going to end me," he huffed, moving to kneel between skinny, endless legs. Pavel wrapped them around his waist.

"Doctor?"

"You're so beautiful, and young, and intelligent, and more than I fucking deserve, but I'm too selfish to turn you away now that you're here."

"Doctor," Pavel purred, and McCoy realized his own hands were shaking, "I want you to be selfish. You are strong and handsome and kind and lovely, and I could not think of a better way to spend my night. Now," and here he wiggled his ass, and McCoy's vision swam with lust, "fuck me, Doctor. I am already stretched, just for you."

He furrowed his brow and he reached a hand down to thumb at Pavel's entrance, which was indeed slick and ready for him. He quickly gripped Pavel's hips to keep from exploding. The damn kid was ready for him, and all he had to do was stick his cock in. Pavel was absolutely incredible.

His eyes slid up to Pavel's, and they locked, hazel on blue, as McCoy slid into that tight, delicious heat. It was almost too much. Waves of pleasure engulfed him, tingling down his spine to curl in his abdomen and squirm.

"God, kid – Pavel," he groaned. He began to move, slow, steady thrusts that rocked Pavel back and forth. The ensign shifted, resting skinny arms around his neck and he pulled him up and towards his face, inches away, and their eyes never left each others as McCoy fucked him.

He was making the most delicious noises – breathy, needy moans, tiny cries, and he'd occasionally clench his eyes shut and murmur something unintelligible in Russian.

"Doctor," he moaned suddenly, loudly, and McCoy shook his head.

"Leonard."

"Oh , Leonard! Faster, please, faster," he begged, mouth open and pink, and McCoy obliged.

Pavel writhed beneath him, becoming a snake in his arms as he rutted against McCoy's body, and then the doctor felt the wetness splash across their bellies as Pavel came. The sight of the boy's face, flushed with ecstasy, and the fucking sound he made when a came, a combination of McCoy's name and please and yes and pure, unbridled pleasure, was enough to push him towards his own completion.

But Pavel grabbed his hand just before he came, then wriggled away, and McCoy slipped out of that warm body. The ensign quickly brought his face to McCoy's cock once again, and he glanced up at him, eyes darkened and begging, and he said, "Come, Leonard. On my face."

That was it. White spurts painted that lovely face, thoroughly debauching it, and McCoy knew whenever he saw the kid walking around the ship from now on all he would ever see was his own semen striping the kid's face.

It was almost too much for an old doctor to take.

He finished and collapsed to the side, boneless, and Pavel followed him eagerly, still licking semen off his face, curling around his larger body as easily as a jigsaw puzzle fitting into it's companion piece. He wasn't sure how Pavel managed to find places to fit his gangly limbs, but he did it, and McCoy didn't really care beyond that.

"Doctor – Leonard – I would like to stay here. Sleep with you. Is okay?"

How could he deny those eyes? He couldn't, that's how. Swallowing thickly, he grumped to cover up his eagerness for Chekov to stay, "Yeah, whatever, kid. You can stay here."

He may as well have said he'd marry him, what with the way Pavel's entire face lit up. Then wet, slippery lips were pressed to his and he reacted on both instinct and choice, pressing back, slipping his tongue into that delicious mouth that still tasted like his cock, and fuck if that wasn't all kinds of kinky.

"Good night, Leonard. I will see you in the morning," Pavel murmured after pulling away, only to bury his face into McCoy's throat.

He smiled into Pavel's hair. "Yeah..yeah, I'll see you in the morning, kid. Good night."