Probably it was just wishful thinking, but McCoy had a feeling that he would have a visitor tonight, and so after his shift ended, he did not go straight to bed. Instead, he selected one of the volumes from his antiquated medical anthology, which he kept at the head of his bunk, and he reclined there, perusing the book, half paying attention to it. He always found reading it a little slow-going, for not only did the grammar deviate substantially from twenty-third century English, but the book was printed during an era when it was commonplace to substitute the letter "f" for the first "s" that appeared in a word. But McCoy took a macabre delight in the antiquated texts. Surely the misguided instructions and philosophies had harmed many more people than they'd helped. But the theories behind some of these practices, for instance the early inklings of psychosomatics expressed as "humours," gave him a certain satisfaction, that there were always glimmers of hope and progress buried in dark and ignorant times.

Halfway into the chapter on "diftempers," his door chime chirped, and McCoy was startled, because he'd begun to nod off. "Come on in," he drawled. Perhaps his answer had been a bit too eager. But he knew it was Spock. He could sense Spock at the door. Or maybe that was just his imagination.

When Spock entered, McCoy looked upon him fondly, even if Spock was his usual, impassive self. "I remember when you used to smile," he said.

For an instant that impassiveness was broken, as Spock recalled his early days on the Enterprise. "I only wished to make the human crew more comfortable. I surmised that imitating their facial expressions might quell their perception of me as a sinister extraterrestrial."

McCoy closed his book and set it carelessly alongside the row of texts, rather than put it in its proper place. "You didn't give us humans much credit for catching on to fakery."

"Indeed." McCoy gestured to Spock to sit with him on the bed, but instead he pulled up the chair, and continued. "I discovered that what makes humans more uncomfortable than not displaying emotion, is displaying emotion in too deliberate a manner."

McCoy gazed into the middle distance. "Oh, I don't know, I'd say your smiles were better than what you started doing after that." He sat up ramrod-straight and imitated Spock's monotone. "Mm, yes, indeed, one of your Earth emotions." He relaxed again and made eye contact with Spock. "So, what's on your mind tonight?"

Spock still retained traces of that urge to imitate human behavior, and so he made an effort to "get comfortable," by leaning back slightly and crossing his arms. When he realized that the gesture might actually make him appear more forbidding, he modified it by instead clasping each elbow with the opposite hand. "I have continued my research into Earth's literary archives, yet I believe I am no closer to understanding what attracts humans to one another."

McCoy tilted his head. "Well, you can't be any further from understanding it than humans still are. Are you asking me what makes a pretty girl pretty?"

"Doctor, is being 'pretty' the only thing required to make someone desirable to a human? I find it foolish to select a mate based on physical appearance, when so many other factors are more important to the perpetuation of the species: intelligence, ingenuity, reflexes, and cardio-pulmonary vigor are just a few. This superficial attraction to features which are, subjectively, aesthetically pleasing, I can attribute to the human male's compulsion to pass on his genetic material, even at the expense of the passing on of better genetic material which may exist elsewhere." Spock ignored McCoy's dubious stare. "But there is another element of attraction that remains a mystery to me. It is the classification of a potential mate as desirable because they possess 'inner beauty.'"

"What's wrong with inner beauty?"

"Nothing, so far as I can tell. What confounds me is how this quality is detected among humans. Humans possess little telepathic ability, and no seventh sense which binds them to the larger intangible mechanisms of the universe. So, how do humans detect inner beauty?"

McCoy needed a moment to formulate an answer, and for that moment he bestowed on Spock an affectionate smile. "Spock, come on now. You're half-human. Are you really going to sit there and act like we're entirely void of an ethereal aspect? Surely in all your years you have felt attracted to someone in that way, attracted to something inside them, that you couldn't see or touch. Even if they were just a lowly Earthling."

It did not escape McCoy's attention that Spock made no effort to contradict his self-deprecatory remarks about humans. "During the time that I was betrothed to T'Pring," Spock said, "I did not assess anyone based on their potential as a mate, because one had already been selected for me. T'Pring's 'inner beauty' was not a factor, as it was expected only that we would, through our bond, assimilate into Vulcan society at large. And in the time since that arrangement was broken, I have been assigned to this vessel, and my duties supersede any personal ventures I might care to undertake. I have not had the opportunity to use any parameters at all to evaluate anyone as a potential life mate for myself."

"Of course you haven't, because Jim gets to them first." McCoy laughed. Spock didn't. McCoy wasn't sure the two of them were on the same page. Spock wasn't really talking about attraction anymore, he was talking about arranged matings.

"Are all mates on Vulcan…life mates?" McCoy asked. Part of him hoped Spock would pick up on what was really being asked, but another part hoped he wouldn't.

"All social practices on Vulcan are expected to perpetuate the stability of our culture. The arrangement most conducive to that immutability is a lifelong partnership which provides a stable household in which to raise children in the Vulcan manner. Many Vulcans choose a mate as an adult, but a marriage was negotiated for me because it was believed my human heritage would prevent my being willingly chosen as a mate. It was important that something be done to assure I was appropriately integrated into Vulcan society."

McCoy couldn't believe how readily Spock was volunteering this information. All along, he'd been trying to drop hints to Spock, and now he wondered if Spock hadn't been hitting him over the head with hints of his own. He might even have been doing it for weeks, and McCoy had just been too dense to realize. "Why are you being so candid with me?" he asked.

Spock cast his eyes downward. "I do not know."

Hmm. That was a strange hint. Now McCoy felt like a fool for mentioning it, and he scrambled for a way to keep Spock talking. "Well, your secrets are safe with me. You know, confidentiality and all that."

"Your obligation to maintain confidentiality extends only to your interactions with patients. Do you presently consider me your patient?"

McCoy did not know which answer would be better, so he ignored the question. I'm gonna go for broke.

"It must have been a strange experience for you growing up, being considered so…undesirable. Then you leave home and half galaxy is falling over itself to get a piece of you. Even with those ridiculous ears. Must be difficult to keep a handle on things." Spock did not respond. "I know a little about how Vulcans suppress emotions and pain. But what about…other urges?"

Spock leaned forward, planting his elbows on his knees. "When not experiencing Pon Farr, a Vulcan does have sexual urges, but they are not so strong that they cannot be suppressed, just like any other emotion."

"But they are strong enough that one might act on them?"

"If one deemed it appropriate."

"Appropriate. Well."

Something was missing from the things Spock was saying. It seemed that the answers to these sorts of questions must carry either the finality of rejection or the gleam of invitation. But his answers remained ambiguous.

For a while now, McCoy had been waiting for a particular signal. It was something in the neck. You turned your head a certain way, to subtly indicate to the other person that you were aware the tension was leading up to a kiss, and you were enthusiastic about facing that inevitability. Then McCoy remembered that Vulcans did not kiss, and he wondered what other signal he should be watching for.

"I give up," he said finally. "Spock, let's pretend I'm not very perceptive, and I don't know anything about Vulcans. But I'd like to. Is there something you're trying to tell me? Right now?"

If Spock himself had been waiting for a signal, apparently it had just been given to him. Without quite standing up straight, Spock moved himself from the chair to the foot of the bed. He reached out and tried to touch McCoy's face with his hands. McCoy shrank back.

"Whoa, you don't waste any time, do you? That was a bit more than I expected."

"I…admire your mind," Spock said apologetically. He thought that's what the doctor had been requesting, but now he knew that he had done something wrong. Perhaps this meeting would be over now. He did not bother to move away physically, for he felt that a great distance had already just opened up between the two of them. "When I was a child," he said, "my elders told me that as I grew older and practiced the Vulcan disciplines, it would become easier to suppress my emotions. But it has not."

"Has it become more difficult?"

"Sometimes it is."

Instead of reaching for his mind, Spock took McCoy's hand. This gesture, he knew, had an innocuous Terran counterpart, but Spock could use it to receive a vague telepathic message from the doctor. He had not been mistaken before. Underneath the doctor's fleeting annoyance, Spock felt sexual desire, and with a bit of concentration he could feel that it was directed toward him.

"You are attracted to me," Spock said, "and yet you resisted my advance. Therefore, I must conclude that you either wish to be taken by force, or else you wish to be seduced. The first option seems less likely, and so I will seduce you."

McCoy considered the merits of the first option for a moment before deciding to just be happy that Spock was interested in pursuing the second option. "I find it hard to believe that you are practiced in the art of seduction," he said teasingly.

"Seduction is the act of inducing or convincing another person to perform a particular act. The ideal outcome of a seduction is for the object of the seduction to believe that the act was their idea in the first place."

"I see. So you bear the monumental task of trying to convince me that it was my idea for us to…um…"

"Have a sexual encounter."

"Encounter, right."

"I have read extensively on human sexual techniques."

"Oh? So those don't mystify you the way human relationships do?"

"With some additional training based on your specific tastes, my calculations indicate that I could sexually satisfy you more efficiently than could anyone else on this vessel."

McCoy breathed cautiously now, as though there were something else inside his ribcage, something that would be crushed if his heart and lungs got too reckless. "And your calculations are always correct, aren't they?" he said, trying to remain still.

"There is no log of that statistic in the ship's computer. However, my personal records show a ninety-seven point four accuracy rating for my calculations, analyses, and hypotheses."

It was becoming clear. McCoy did not know much about chess, but he understood now that Spock had merely been adhering to the touch-move rule: Do not touch a man until you are ready to move him or capture him.

Nor was McCoy a gambling man, but a ninety-seven point four percent chance of sexual ecstasy sounded like a good bet. "Mister, you got yourself a deal."

Off came the blue uniform shirt in a flash, but as he was pulling up the black shirt underneath, the air hit his bare skin, and McCoy realized that what was about to happen would be very unusual. Here he was, halfway to being naked, and Spock was going to be naked too, at least he presumed so. Something about that was…not right.

But it was so surreal, it was like it wasn't happening at all. I can do this, he thought, because I'm not doing it, not really. He pulled off the black shirt, balled it up, and held it up against his chest, a nervous attempt to cover up again. He called out, "Lights at ten percent."

Spock found this incongruous. "Doctor, do you not wish to see me?"

"Oh, I do!"

"Then you do not wish for me to see you?"

"Eh…kind of. I mean…Spock, do you remember when we were on Melkot, and you said you were afraid? Are you afraid now, too?"

"I admit that at that time I was being platitudinous. I do not feel fear. So far as I understand it, fear tells a human that it is unwise to enter into a situation because it entails a risk of some kind. For Vulcans, logic sufficiently fulfills this role. Vulcans calculate the risk and proceed accordingly."

"Pardon me then, I suppose I should ask: do you think this might be too risky?"

"I have not completed my calculations at this time."

McCoy gritted his teeth. "For the love of…Spock, would you just hurry up and get naked with me so I can start being okay with it?"

Spock was puzzled by the whole of McCoy's request, but he understood the imperative portion of it, so he began to undress.

There was something a bit prurient about the way Spock's boots hit the floor, one after the other. It was the implication: hearing them drop and knowing what it meant. McCoy thought about the strange, cool air against his skin. "Do you…How warm do you want it? Just say so."

"Computer." Spock inclined his head just slightly toward the ceiling, an imitation of the human tendency to do so. "Raise temperature to thirty degrees Celsius." He smoothed his tone to continue speaking to McCoy. "That will be comfortable for you?"

McCoy was now completely undressed, trying to settle himself on his bunk in a way that made him feel less naked. He had not even heard the temperature Spock had asked for. "It's fine. Get over here, would you? I'd feel better if you weren't so far away."

Spock, for his part, was also not entirely comfortable. Though he had accumulated a vast store of intellectual wealth on the subject, he was not practiced in the sexual arts, and had already decided, much to his dismay, that the learning process could not be made mathematically pure. In an attempt to neutralize this concern, he had given McCoy the impression that he was secure and confident in his abilities. This was only a projection, stemming from his conviction that nothing was to be gained from shying away.

Something new was motivating him now, from deep inside. Like Pon Farr, it was an imperative feeling, but without the accompanying sickness and pain. He felt like an animal who could move freely and safely, because it instinctively knew that hunting season was over.

He kneeled on the bed, leaning tentatively over McCoy. All their nervousness and discomfort could be gleaned by the fact that neither one of them at this point had an erection. McCoy kept tilting his head, waiting to accept a kiss, but none were forthcoming. Instead, Spock put his hands on McCoy's body, picking up scraps of inconsistent emotion as he went. His fingers slid over a tense bicep, and he sensed the anxiety. A moment later, as he caressed a pectoral muscle, he could feel the first traces of McCoy's arousal, and so he thought he'd found an erogenous zone. But when he went over it again, the anxiety would return. He stayed put anyway, stroking the hair over McCoy's sternum, then drifting over to test the nipple for its sensitivity and erectile properties.

McCoy turned his face away and chuckled nervously. "You know, when I was in medical school, I once asked a professor why men had nipples. He told the class they were decoys, to attract real nipples."

Spock had succeeded in making his tiny pink test subject hard, and he continued stimulating it with the pads of his first two fingers. "Only one set of chromosomes determines the gender of a humanoid," he said. "The genetic code for nipples is an autosome, which are gender-neutral. This universal template is a more efficient way of structuring the genome."

"I like my explanation better." McCoy inhaled deeply, detecting the scent of Spock's body. "Mmm. There's something about the way you smell. It makes me feel a little…ooh." It had never occurred to him before that Spock might have been giving off pheromones all this time, that were affecting him, even if he could not smell them. This thought frightened and excited him.

Spock lowered himself a fraction. "When I first traveled to Earth, I calculated a seventy-nine percent probability that humans would find my scent pleasing, based on data regarding preferred odors."

Ignoring the rather dry commentary, McCoy pulled Spock to him, and settled himself so Spock could rest comfortably on top. At that point, Spock was overcome with sensation, because now his genitals were pressed against McCoy's, and this had happened sooner than he'd projected. He felt McCoy's penis finally becoming erect, which made his own organ hard in response. Typically he used a series of mental exercises to forestall an erection, when one occurred, but in this case he did away with those drills. Instead, he gave in to the instinct to rock his pelvis back and forth, enjoying the new sensations even as he caused them to increase.

After a few moments of rubbing, Spock felt a little spot of wetness on the skin over his right iliac crest. He identified this as one of the preparatory secretions humans produced to neutralize the acidic environments which semen must endure. It seemed illogical to Spock to have such a system; why not just eliminate the acidity? Then the secretion would not be necessary, and the system would be simplified. Ah, but then again, in the temperate climates of Earth there were microbial considerations. He would study this later.

As he began to feel an increasing amount of this moisture, Spock desired to examine the phenomenon in progress. He pulled away from McCoy and observed the doctor's erect penis. To encourage the secretion, he grasped the organ and squeezed gently, sliding the foreskin up and over the crown until a drop of moisture welled out. It was thin and clear. He had read conflicting reports on the taste, consistency, and pleasantness of that secretion, so he would have to experience it to make a decision himself. He crawled backward so that he might put his mouth on McCoy's penis, to have a taste of his fluids.

Vulcans had a term for this technique, guv-kru'shok, which was a contraction of the more literal si guv kruslar shok, however, the act was not widely practiced. Some Vulcan anthropologists, having been unable to locate references to the act in historical literature, postulated that Vulcans had eschewed this practice entirely, after Surak's philosophies had taken root, and that a designated term was introduced into the language only to accommodate translations of texts from other worlds.

Spock's own first impression was not one of taste but of noise. McCoy began making small, sharp noises in response to this stimulation. Spock applied his tongue more generously, and the noises were soon accompanied by squirming.

"Unh, Spock, I'm gonna come of you keep doing that."

Spock paused. "Is that not the object of the endeavor?"

McCoy let his head loll to one side in resignation. "Of course Vulcans wouldn't understand pillow talk."

So far Spock had been using his mouth for two things, and at this moment McCoy seemed to prefer one over the other, so Spock quit talking and continued what he had been doing, and McCoy was happier for it.

McCoy stroked with one hand over Spock's head, to encourage more than to guide, and Spock felt the doctor's pinky ring, warm with body heat, brush against the tip of his ear.

More than once, McCoy made a noise, and Spock tasted a little more of the saltiness, and he suspected the culmination was imminent. But the true end was unmistakable. Beneath Spock's hands, McCoy's thighs began to tremble, and the noises he made became continuous.

For the first time in a long while, McCoy was not in control of his own pleasure. If he wanted, Spock could dole it out in tiny portions, or he could gorge McCoy to the point where he would be unable to appreciate it. Luckily for McCoy, Spock was not cruel.

McCoy happened to open his eyes for a look just as Spock took his mouth away for a moment, to catch his breath. The sight of this sleek, dignified Vulcan with a strand of saliva suspended between his lower lip and the head of McCoy's cock was beyond belief. It gave him a spike of pleasure that hit him square in the gut. His arousal continued to build as his shaft was taken in again, rubbed along the subtly ridged roof of Spock's mouth. Then quickly he was taken even deeper, and the glans hit the velvet of Spock's soft palate, and he came. He filled Spock's mouth with a burst of salty, bitter warmth. Spock kept sucking until McCoy was soft, and too sensitive to be touched. He did not want to push Spock's head away, and make him think he was being rejected. Instead he twisted until his soft penis slipped from between Spock's lips, lying moist and spent against his thigh. With his eyes closed, he concentrated on the feelings coursing through his body, his heart still squeezing hard to distribute euphoric chemicals to his extremities.

Spock made his way up the bed, hovering over McCoy's limp, glowing body. He had never been in the presence of a human who had just experienced sexual gratification. He touched McCoy and found his emotional state much simpler, and definitely more agreeable. How did humans get anything accomplished, when they had not the disciplines to stifle their desire to achieve this state?

He leaned down to whisper in McCoy's ear, "How may I find relief, with you?"

"Mmm…You can…Can you just lie here with me and let me relax? I'll help you in a minute."

Spock trusted that McCoy would make good on this promise, despite the often-nebulous human definition of "a minute." He sidled up to McCoy on the narrow bunk, trying to find the least awkward places to drape his limbs. He buried his nose in McCoy's hair, nuzzling it, down to the ear, then back to the nape of his neck. McCoy's head fell lazily to one side, presumably to accommodate this.

As McCoy's breathing slowed, Spock suspected that he was dozing off. He could sense a sort of bubble growing around the doctor, a bubble of warmth, completely free of tension. He suspected that he would be unable to pass through this bubble to get to McCoy. Already seven point three minutes had gone by. But then a languorous hand reached over to touch him, and Spock lost track of time.

McCoy had never actually seen Spock's penis before. The only Starfleet medical exams thorough enough to require disrobing were conducted prior to a mission commencing; the routine exams that McCoy had performed on Spock since he'd been transferred to the Enterprise were done with standard medical scanners, which paid no heed to clothing anyway. For almost as long as he'd known Spock, he'd had the typical human curiosity about the size and shape of his genitals, if they were different in any way. Now that he saw them, he was too relaxed to feel either relief or disappointment that they closely resembled human organs.

There was still an alien aspect to it, though, holding another man's cock in his hand. It didn't feel the same way as holding his own, not really. He could hear, seemingly from far off, Spock's breathing. It quickened as McCoy woke up a little, and began to give the shaft increasingly vigorous strokes. What was in his hand was everything Spock wasn't: Proud. Flushed. Demanding. He was focusing now, switching from an overhand stroke to an underhand so he could speed up. Aside from the slight variation in his breathing, McCoy could not discern that Spock was feeling any sexual pleasure. His first and only real indication was the moment Spock flung his arm out to grip McCoy's bicep tightly as he spent himself on McCoy's belly. He made no sound, save perhaps for a little hiccup and sigh.

McCoy waited for Spock to loosen his grip, so that he could lean over to grab his discarded shirt off the floor and clean himself up a little. But instead Spock held on more tightly and pulled McCoy to him so that the doctor feared he might be crushed. Spock's seed was smeared over both their bellies, but Spock did not seem to notice. His hand swooped down from McCoy's arm to his hip, holding him still tighter.

"Spock," McCoy gasped. "I'm glad you like me…but I can't breathe."

Spock loosened his grip fractionally, just enough for McCoy to get air in his lungs. He dared not protest further. Spock was radiating something very intense and he did not want to try to interfere with it. He lay still, feeling the still-warm seed drip down from their bellies onto the sheet. Sweat accumulated on his skin under Spock's hands.

Even when Spock released him, the bunk was so narrow, there was hardly anywhere to go. "I did not intend to discomfit you with my behavior," Spock said. "It is an effect of the oxytocin."

McCoy smiled with recognition. It had been a while since he'd heard about oxytocin. It was not the sort of thing that came up much on Starfleet missions.

"The Cuddle Chemical," McCoy said. "That's what the medical students called it. Well, some of the women called it 'the traitor within.' You know, even if you were just after a one-night stand, when you come and your brain orders all that oxytocin to be released, it makes you feel kind of attached. To the person you came with."

"Indeed. Presumably the purpose of the chemical is the same for humans as for Vulcans: to encourage a long-term attachment. Vulcans attain this bond much more quickly and easily than humans because they - we - produce on average five point six times more oxytocin during an encounter than a human. Males and females, both."

McCoy shifted to keep his arm from going numb. "So, in the future, I can expect frequent instances of you crushing me half to death in this bed?"

"Not only in this bed," Spock mused.