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Kirk never turns down a challenge. It's an attitude that serves him well, how he ended up the youngest captain in the Empire. But Bones just might be his biggest challenge yet. Kirk strokes his fingers through the man's dark hair, just to see him pull at the restraints holding his wrists to the bed. Those soft little gestures piss off the good doctor more than anything and he only gets away with them when Kirk has him like this, trapped, tied down, forced to suffer the imitation of love. He does it just to hear him growl.
They've been at this for weeks, but Kirk is determined to get under Bones' skin and make him say it. He's going to get what he wants. And tonight is the night. It's not enough to sink into Bones, not enough to force the man to ride him or wrap his perfect lips around Kirk's cock. He's going to beg, and he's going to say those words that Kirk is itching to hear.
Kirk strokes his hand down from Bones' hair, fingers pressing over the line of his spine. He's sucked and bitten a trail of angry bruises that lead down to his ass, like a path to point right to where Kirk prefers to spend his nights, buried to the hilt between those cheeks.
"Why don't you get on with it?" Bones snarls, but it only makes Kirk smirk, the edge of need cutting through that harsh tone. The best part has been making Bones like it. Kirk isn’t one of those fools who spends all his time on his partner, willing or not, unless it's someone he intends to keep. And he intends to keep Bones for a long, long time.
Bones is a cruel and sadistic man in his own right, and that's what makes Kirk want him. He's useful. And now, now he'll be loyal. The thought makes Kirk ache with the need to fuck him, to give up this slow torment and wring out everything he possibly can from Bones.
Instead he pinches the base of his cock and counts to ten. Bones growls other obscene things, definitely aware of the distraction. Kirk takes a deep breath and slaps his ass. "Why don't you be a good boy for daddy this time, hmm?"
"You sick bastard," Bones snaps. "If you think I'll--"
The retort turns into a choked groan as Kirk roughly presses two fingers into Bones' ass. It's a surprise more than anything. Bones knows better than to answer his captain's summons without first preparing himself, but Kirk still enjoys the hot tightness around his fingers. Bones comes to him of his own accord, without having to be forced.
"I think," Kirk hums and leans down to bite the swell of his cheek, "You'll do it. For me, Bones. Because then I'll give you what your slutty little ass wants." He twists his hand, pumping his fingers in and out slowly, back to an agonizingly slow pace. "It's fair."
"Fair?" Bones says through gritted teeth. "You wouldn't know fair if it reamed your ass!"
Kirk barks out a laugh, takes it with a hint of humor that only comes from having his hands on a helpless, naked Bones. Well, never helpless, not completely, or Kirk wouldn’t care enough to take him apart at night between the sheets, or bent over his desk, or on his knees beside a biobed. Wherever he uses Bones, however he uses Bones, he’s not tired of it because he’s not broken yet.
"This is why I haven't killed you yet, Bones," Kirk chuckles with a sort of fondness that makes him press a third finger into Bones' hole roughly.
"And why I'm going to kill you as soon as I get my hands free," Bones threatens. God, he's driving Kirk crazy with the way he's breathing each word, like it's hard to face. He's giving in, shuddering and cracking. Kirk has been pressing all his buttons and has him tuned the way that crazy, half-robotic engineer tunes the warp engine. To a perfectly fine point, the point where everything is working the way Kirk wants it.
"Remember when you took my whole fist, Bones?" Kirk cooes, projected innocence and seductive manipulation. He prods Bones' ass with a fourth finger and listens to him try to breathe deeply. "It made you sound so pretty when you gasped and couldn't come up with any of the right words to make me stop."
"Y-you... Fuck!" Bones lets out.
"You know what I want to hear," Kirk continues. "If you don't want a repeat of that tonight, just say it. Be a good boy for me."
Kirk starts to press that finger in and spread them, searching for Bones' prostate and getting a strangled cry when he finds it. His muscles clench deliciously tight and he strains against this restraints with renewed fight.
Kirk keeps pressing and stroking, frowning as he listens to Bones moan incoherently. Maybe he's not ready. Maybe he won't give in tonight. Kirk doesn't like that idea. He pushes his fingers in deep and thumbs at the stretched flesh around them.
"F-fuck, p-please!" Bones cries out. "Fuck, please d-don't!"
Kirk hesitates, waiting but tired of the stalling. Just a little more pressure and he'll have his hand--
"D-daddy, please!" Bones chokes out.
Kirk groans, pulling his hand back lightning quick and grabbing a handful of Bones hair at the back of his head. It's so good, it's perfect. He's won and he can't wait any longer.
"Such a good boy, daddy's good boy," Kirk murmurs fervently as he lines up his cock and drives into Bones with a deliberate thrust.
The doctor trembles apart beneath him, Kirk's hand pressing his face into the bed as he fucks him with long, almost punishing strokes. It's the only way he can take him now and Kirk kind of wishes he had the patience to better savor this moment--but he can come back to it. For now, he pulls up on Bones' hair so he can bite his ear and growl at him, "Keep saying it, Bones, keep saying it or I won't let you come."
Bones doesn't hesitate, doesn't even seem to consider it. "Please, daddy, please just--daddy, daddy!"
Kirk is pleased enough not to be cruel, to even be generous, letting go of Bones' hair to grasp his leaking cock and pump it in time with his brutal thrusts. And god, Bones, delicious, perfect Bones, he keeps repeating it now. Daddy, daddy, daddy.
Kirk feels him tense and shake through his orgasm, the last cry wordless, but close to what he's supposed to be saying. They'll have to work on that, but for now, Kirk keeps fucking him through it, until his fingers are coated in Bones' come. He's close too, so fucking ready, the snap of his hips becoming erratic. Kirk brings his dirty fingers up and forces them between Bones' lips. He doesn't have to tell him to suck, Bones just does it, just takes it.
Kirk shouts his release, stuttering to a stop buried deep inside Bones. His voice drops to a growl as he empties himself into the doctor’s shapely ass and nothing matters except that he’s got such a perfect whore at his disposal and he’s used him well tonight.
"Good boy, good boy, good boy," Kirk finds himself saying, his eyes screwed shut. "Thank your daddy, Bones."
"Fuck," Bones groans, around Kirk's fingers, still in his mouth. "Th-thank you, daddy."
Kirk rests over his back, not wanting to move yet. In a moment he'll get up and clean up his good little boy, but for now, he strokes his fingers through Bones' hair and smirks.