Written for a kink bingo square, for K/S Day, and for cannedebonbon, because I've been promising her more of this pairing for months. YES I'M TRIPLE-DIPPING, DEAL WITH IT.

Warnings: Spanking, D/s

Ever since Jim had retreated to Spock's desert home a few days ago for a little R&R, the more aged version of Jim's first officer had been downright frisky. Jim was probably first person in the universe to attach that word to a Vulcan, but there was just no other way to put it. Spock was constantly brushing their fingers in passing, and pouncing Jim in the shower, and letting dinner burn in favor of a spontaneous and very illogical round of couch sex. He just couldn't keep his hands to himself.

Jim never dreamed he'd see the day when someone could leave him in the dust.

Almost four months had passed since they'd started hooking up, and while Jim had always been pleasantly surprised at Spock's libido, this particular shore leave it was spiking to stratospheric levels. So he lived in a state of perpetual exhaustion and endless hard-ons, conditioned to react to Spock's mere presence. Wary every time the ambassador was within a ten foot radius.

But the sharp pinch on his right asscheek still caught him off guard.

He jumped and almost dropped a measuring cup held at eye level, spilling water all over himself. By the time he gathered his composure, Spock was cutting salad greens further down the counter. If he were human, he would have been whistling. Jim fixed him in a hard stare, and Spock pretended to notice after a moment or two, adopting a look of near-perfect bewilderment. The man might wear dignity like a cape in public forums, but he couldn't conceal the mischief that crinkled the corners of his eyes. Not from Jim, anyway.

Jim slammed the faucet off, snatched up a towel, and deliberately patted his hands and shirt dry without taking his eyes off the ambassador. Still no response, unless he counted Spock returning to work with a faint eyebrow shrug, as if he had written Jim off as a hopeless klutz. So Jim kept steadfast on his progress toward tomato soup, measuring water for the second time in as many minutes, every sense on high alert.

His opportunity for revenge came a few minutes later when Spock scooted behind him on the way to the sink. Jim took aim, reminded himself he didn't have to hold back, and planted a hard slap on Spock's ass.

Spock froze but didn't move right away, giving Jim plenty of time to dart out of reach. He didn't bother playing coy when Spock fixed him in a cool, dispassionate stare. He couldn't have wiped the grin off his face if he tried.

Long, silent seconds passed with neither of them blinking. Jim's brain helpfully imagined a tumbleweed rolling between them. His hand hurt a little, and his fingers twitched, not unlike a gunslinger in a standoff. Vulcan muscle density was serious business.

Then Spock's stare turned calculating, and Jim's stomach dropped. But it was the pleasant kind, like from a well-executed shuttlecraft flip, where the danger wasn't real so his body translated fear into pure excitement. He shuffled back a few steps, trying to use the kitchen island as a barrier, but Spock was faster than a man his age had any right to be.

He scooped Jim up in nothing flat and began marching toward the living room. One arm looped around Jim's waist, carrying him like a sack of flour. Jim yelped in protest and tried to free himself – he knew from past experience that all it took was a well-timed twist to evade Spock – but he was laughing way too hard. He had lost control of his muscles, and all his strength just kept pouring out of him before he could direct it toward self-defense.

Besides, he couldn't actuallykick and punch his way to an escape. He didn't want anyone to get hurt, and between his restrained, dangling self and a man who was old by Vulcan standards, chances were pretty good that any serious resistance would end at the local health clinic. So with limited options and no time to act on them, he decided the best option was to hang like a dead weight.

Not his best plan, admittedly. Spock's progress didn't flag, not even a little bit. He sat on the edge of the sofa and promptly dumped Jim face-down across his legs. His thighs dug into Jim's chest, making it harder to breathe the more he struggled, and one strong arm settled over Jim's shoulder blades so he couldn't lever himself up.

"Hey!" Jim flailed, still stifled by his laughter, and got exactly nowhere. "Let me go!"

"You lack respect for your elders," Spock said with mock gravitas. "I believe discipline is in order."

"You started it." Jim pointed out. But most of the accusation sounded like gibberish, because Spock had just yanked his pants and briefs down to the top of his thighs. And planted a firm slap on his ass.

The sound and sensation wiped his mind blank. A lingering sting buzzed through him, weird but not unpleasant, and Jim almost choked on sheer disbelief.

"Okay, that actually kind of hurt," he said between snickers. He squirmed again, testing Spock's hold. The delicate friction of his pants and briefs where they were stretched tight over the front of him was a tease, and he could feel his cock begin to stir. His cock was easy like that.

"That is the purpose of this exercise, is it not?" Another firm smack, this time on the other cheek, cut off any response. Then Spock added, in a gentle tone that seemed entirely removed from the situation, "Should you truly desire I stop, you need only ask."

Jim was curious about where this was headed, so he nodded to show he understood. This was different than anything they'd done so far, and one of Jim's greatest weaknesses was novelty. A few people had tried the dominance thing on him in the past, but he could never quite take it seriously. It was a lot easier to take seriously when the person in charge was about three times stronger than him.

In any case, Spock took that permission and ran with it. His slaps were steady, firm and practiced. Confident in a way that could only come from a century's worth of experience. His hand seemed to target the most sensitive possible locations on Jim's ass with the kind of precision phaser technicians could only dream about. Jim was reduced to cringing over Spock's thighs, breathless, clutching at Spock's robe where it draped and pooled on the floor beneath them. His ears rang with the sound of the onslaught and his own thudding heartbeat.

"Damn, Spock," he said during a brief lull. Protest or encouragement, he wasn't sure.

"Ambassador," Spock said, stern and casual all at once, and Jim shuddered.

"So that's how it is, you kinky bast- ah!" He recoiled at the sharp slap to his upper thigh, harder than the ones before. "Sorry. So that's how it is, Ambassador. Ow!" Okay, so there could have been a little sarcasm in his tone, but that certainly didn't merit the ensuing whack. "Hey, what the hell! I said it. FuckingOW."

Jim decided maybe it was best to cut back on the color commentary. The next half-dozen blows came and went, and he made sure he didn't so much as gasp. He grit his teeth together and called upon the stubborn willpower he usually reserved for dealing with the other Vulcan in his life, determined to stay quiet no matter what happened. The hurt might be going straight to his cock, but he had his pride. He wouldn't give Spock the satisfaction of making him cry out, of knowing how bizarrely this was affecting him.

Because Jim Kirk would never pass up on a challenge, even one he had to invent himself.

Spock paused for a few moments, then made a low, pleased sound in the back of his throat. "Your behavior is much improved already," he said. And damn if Jim didn't have to literally bite his tongue to keep it that way. It would take more than this to beat the smartass out of him, he thought.

Maybe Spock picked up on the attitude problem, because he alternately kneaded and caressed the stinging flesh of Jim's ass before lining up a string of quick strikes all up and down the backs of his thighs. Each one seemed perfectly aimed to make him flinch, which pushed his hips forward, which graced his cock with the slightest bit of friction. The head was trapped tight against the waistband of his briefs now, and the slaps came like a hail of pleasure and pain, a double infusion of heat, squeezing Jim between a rock and a hard place. Or a hand and a hard place. Jim almost laughed aloud at that, teetering on the edge of overwhelmed.

All right, something was definitely wrong with him. He was getting giddy, for God's sake.

Spock switched tactics and kept chipping away at Jim's resolve with the single-minded concentration of a Tellarite at a buffet. He struck the same few spots over and over now, rotating between the center of each cheek, the inner curve toward the crack, the dip where ass met thigh. Jim thought he might be varying the strength, but there was no way to tell for sure. It was all equally painful, and as far as his cock was concerned, equally interesting.

Soon his mouth fell open against his will, ready to betray him at a moment's notice. Torture and pleasure he could handle, but both of them combined? He was hot in ways he couldn't decide if he liked. His ass prickled with a thousand tiny needles and burned like he was backed up to a fire. Sweat traced the curve of his neck, glued his clothes to his skin, and there was a growing wet spot on the front of his briefs. The next time Spock paused, he started to speak without knowing what he'd say.

"Ambassador, I–"

"Silence." Spock dragged both hands up and down his back, pushing them under his shirt, a light but comforting massage. The touch lingered long enough to give Jim a chance to back out, but backing out was the last thing on his mind now.

Especially when, without warning, Spock pressed two fingers against his hole and rubbed there firmly. Jim whimpered in spite of himself, curling over Spock's legs, lifting his hips back into the sensation. He could practically feel the nonexistent Vulcan smirk on the back of his head. Then Spock's hand crept lower and cupped his balls through his briefs with a perfunctory possessiveness that made him shiver, which wrung an undeniable gasp out of him, and he was gone. Any trace thoughts of dignity and self-control went straight out the window.

He started rocking against Spock's thigh, desperate for an outlet, for any kind of relief. Half-stifled cries escaped him, the discomfort of compressed ribs drawing his breath short. Almost immediately Spock tightened his hold on Jim's balls to the point of pain. A stern but effective warning. Jim moaned and froze in place until the hand released him. He shook with the effort of holding still.

Suddenly Spock grabbed a fistful of Jim's hair and tugged his head back, just high enough that he could see dark Vulcan eyes glinting in his peripheral vision. "You will not attempt to stimulate yourself again," Spock said. "Understood?"

"Yes, Ambassador." The reply came out in a voice foreign to Jim, meek and compliant.

Spock went back to palming his balls, and Jim sucked in a breath between his teeth. One hand stayed there, restricting his movement, and the other returned to spanking him patiently. And God help him, Jim wanted to beg. He had thrown in the towel hard enough to bust a hole in the floor boards, and he was so close to incoherent begging he could taste the shape of the words on his lips. He would do anything to pull the knife's edge of desire out of his chest.

Right before he snapped, finally, finally, Spock took mercy on him and pulled his briefs farther down his thighs. His cock caught on the waistband, and he hissed as it leapt free and struck his stomach, smearing precome against the fine screen of Spock's robes.

But the relief was short-lived, because this was unlike any erection Jim had experienced in recent memory. It felt impossibly heavy dangling beneath him, a blunt and throbbing ache, an unwieldy extension of his body. The faint drafts in the room were like lewd whispers against his skin. He was an exposed nerve, a mess of sensations; the sharp, dancing pain across his ass, the dull pleasure-pain of his cock, and the desert heat that must have infiltrated the house because it was boiling him alive.

Spock started caressing his smarting flesh again, and it occurred to Jim that the special Vulcan hand sensitivity might be doing something to Spock that he couldn't quite understand. "Please," he said, pushing back against Spock's palms with what little strength he had left, aiming for persuasion. His vision swam, and he shut his eyes, seeking refuge in the darkness. "Oh God, please…"

"Jim," Spock murmured above him. His voice was hoarse, and it reminded Jim of deep wells and autumn nights. "Words cannot express… you have indulged me more than enough for one day."

Jim whimpered in relief and pitiful anticipation, his every muscle going slack. Spock slipped a finger inside him, seeking out his prostate with benevolent efficiency. Reached between his legs with the other hand and took the base of his cock in a loose grip.

Jim hardly got the chance to move his hips before he came, crying out brokenly. His orgasm felt strange, a full-body tremor that didn't end so much as taper off by slow degrees. The spasms started behind his navel and rippled outward, devastatingly strong at the point of origin, reduced to pleasant tingles in his extremities. By the time he regained some semblance of awareness, his cock was soft, and his arms and legs were leaden, and a marvelous afterglow had slipped over him like a silk sheet.

Then Spock was shifting him around, guiding him to the floor, saying something that took several long seconds to register. Only when he situated Jim between his thighs did the word snap into place.

"Kneel."

"Yes, yes, please," Jim murmured senselessly, grabbing onto Spock's thighs for support. Only dimly aware of what was in front of him through half-lidded eyes, he took his cues from sound and touch alone, from Spock's gentle hand on the back of his head. He nuzzled his face into the soft folds of the Vulcan robe obediently, parting his lips as Spock guided him to the source of that familiar alien musk. He closed his mouth around the tip of Spock's erection and moaned in absolute bliss.

The bitter-spice taste flooded his tongue, better than cold water after a long, exhausting hike. Spock was already slick enough that Jim could pick up a good, even pace without any trouble. He flattened his tongue to push against the sensitive underside, and Spock's faint grunt sent vicarious pleasure rocketing through him, kicking up aftershocks in his core.

God, how must he look right now. Disheveled and sweating, trembling on his knees, sucking cock like his life depended on it. Tangled in his own clothes, pants and briefs bunched around his legs. Bare ass exposed to the whole room and bright red as a sunburn. The very thought was enough to tie knots in the pit of his stomach all over again. Heat pulsed out from the broad, stinging swathes of skin where he was struck, driving his rhythm and keeping it steady. Anchoring him to this moment and this moment only.

He could tell when Spock was getting close from the faint sounds he made, from the way he gripped Jim's hair a little tighter, and Jim went for broke. About half the time when he tried this, he couldn't make it past his gag reflex, but today he didn't even have to push himself. It was like his body just melted comfortably to accommodate the intrusion, like his throat was made for it, and Spock slid in smooth to the hilt. Jim swallowed around the warm, thick length of him, inhaling his scent, nose buried in soft gray hair.

Spock shuddered and emptied into him, Vulcan poise reduced to strangled gasps. Jim did the best he could, but had to pull back halfway through or risk a coughing fit. He was determined to make up for it though, licking and sucking every spilled drop from Spock's skin. Had he always tasted so damn good? Jim couldn't bring himself to care; he was drunk on the taste, and it took some wincing, strained requests and an intervening hand on Spock's part to pry him off.

They rested there on the couch and the floor, and Jim lost himself for awhile, drifting in a sweet, sultry haze. Maybe this was what a true meditative state felt like, that fabled peace of mind he could never reach even with a fantastic instructor. The pain on his ass was a dull background hum, silencing all restless thoughts. The carpet was soft under his legs, and Spock's robes were soft under his hands, and all he wanted was to collapse and sleep for days, wrapped tight in this feeling.

"I'm kind of a masochist, aren't I?" he mumbled against Spock's lap.

A cool, wrinkled hand combed through his hair, sparking raw sensation down to the tips of his toes. Jim leaned into the touch, drowning in the quiet affection that poured over him and trembling at the graveled reply. At the promise it contained.

"Affirmative."

A/N: Happy K/S Day everyone!