A/N: Kirk's musings and justifications :)
For Kirk it started like a joke really; nothing serious at all. His First Officer Vulcan was such a good material for teasing, and in his vast intelligence he would believe such puns you wouldn't believe, all you had to do is to keep a straight face and he would be unable to tell between truth and a joke. Like that time he tried to find "ichy kuchy butchy bu", or something quite like it in linguistic banks, and was very surprised to find nothing. It was hilarious. Not that he meant anything malign with his jokes, but time on the ship passed slowly and good laugh could keep him through exhaustingly boring mapping of newest nebula without life forms. But truth to be told Spock turned out to be quite of a player in the games of puns, he was far from simple toy and that made it immensely more fun.
It was even better to watch from aside as Spock, in his straight Vulcan way would just say things to annoy and never miss a beat. He, himself was more than once stunned when he would feel sting of defeat. In time their game became strategic platform, like large play of chess in which actual chess served like board in which they casually kept their score. At least Kirk was convinced Spock has the score in his Vulcan mind, and he would ask if he believed Spock would tell him the real number rather than faint innocence.
It was an innocent game in the beginning while Kirk still believed his First Officer was in fact innocent and sexless creature, even more emotionless. Emotions were first to be exposed, but Kirk would never discus that. Except he would risk for his Vulcan to withdrew from their game, he knew emotions were something Spock detested and tried to banish. It would just be bad manners to point his failure out. Of course he teased him about it constantly, but it was just put down by invincible eyebrow or two. Kirk simple adored when he did that.
Later on Kirk discovered rather animal and primal sexual side of his friend, and he almost died from that discovery. He would still rub his neck when he would think about it. Still it didn't turn Kirk down, on contrary Spock's sexuality became something of personal interest of the Captain. But he was still unwilling to admit to which content. For now he told himself it was just curiosity, nothing more. He knew Bones would tell him it was bull, but Bones liked to do that.
Innocence, Kirk suspected afterwards, was just a convenient cover for him to avoid discussing such matters. Kirk liked to challenge even that, like that time he put him on the spot to explain sex to young ensign. He would crack every time he would think of that.
That left Kirk with acknowledgment that his First Officer didn't just play a game of puns and retorts with him, and consequently with Bones, but more so that he knowingly matched his every move in that other field. One Bones never entered with him, or Spock. Bones was a women's man that much was clear. It matched his old fashion nature. Spock on the other side was hard to read, it took long for Kirk, after he determined that there is a sex drive, to confirm that men would be more acceptable than woman. Kirk himself was a player that liked all colors and shapes, gender or species weren't issue for him. Issue for him was that nobody would hold his attention for sufficient time to develop something greater than passing gratifying experience; nobody, that is, except his First Officer Commander Spock but Kirk didn't give much attention to that for a long time. He assigned it to their constant companionship on Enterprise, ease with which he could talk to Spock, and his quiet attentive nature.
There was no need to dwell upon it, because Spock was always there, and everything Kirk needed he would get. Well except gratifying encounters in bed, which he would get on occasion from passing females. He was the one to admire females features, but as time passed he found himself more and more distracted from a task of luring women to his side. Spot was already taken, but he didn't think of it much. As he said once to a passing alien and ancient human, if he get what he needed from that relationship what is the wrong with that.
After kiss-pain-away incident Kirk had one more piece of information about his Vulcan, one more level of puns he could conduct without detection. It was early in their curious and long relationship that was strained with puns and later on real disappointments, but Kirk knew enough to make that piece of information in motion. It was early enough to do it without second though, without burden that it could cost him something.
He discovered that Spock was able to overcome some of his inhibition when he would think his help is needed. Spock just couldn't turn away from helping. Maybe because of that Kirk started later on connect need to help with love, but that kind of subtle changes in his world view were still hidden from his sight. He wasn't in pursuit of something serious; he was just having some fun making ship life more agreeable. Simple kink in the back was the start. He just have to show he's in pain, throw in a bait for the ego, which Spock had in great supplies, that Bones had clumsy fingers and couldn't do anything if you're dying from spine distortion. Very soon skilled, warm, and exceptionally strong hands were on his back, correcting his muscles.
It was a pleasant victory because he would get a massage, victory, and undetected inspection of sensation Spock's fingers would send out to his back. Frustrating enough clothes would always get in the way of precise detection, but surely there was something there, something tangible and quite enjoyable. Down side was that he really had to be in pain, because he knew Spock would know if he tried to lie. Second thing he learned that it would never happen in public, so Bones would never witness such aid from logical machine. He tried once, on the bridge. Result was more than disappointing. It was frustrating, and even worse, Spock got to give him one of his disdain looks; like it was such a foolish attempt. Kirk knew otherwise, he knew that there was a chance for his hand just to reach out and do its familiar thing, just if that ensign wasn't there, but he would be fool to try again. That line of action was closed down by poor judgment in position of his men on the bridge. Or rather women, women were so easy to make do things for you, there were no need for complex strategic measures and planning ahead. That kind of thoughts would bring Kirk back in pursuit for something easier, but soon he would be back exchanging smiles with his First, because he was immensely fun to talk to, especially when he could just tease the hell out of him.
Besides, Kirk would conclude his mussing whenever he would try to straighten up his behavior, it was most unlikely for Spock to really act on their banter, or that he would ever submit to admit his deviations from perfect Vulcan. That was his safety wall between them, it enabled Kirk to act incredulously enchanted and amused, to show his every tickle Vulcan provoked in him. He sometimes allowed himself thought that Spock is perfect training ground. Things that made his Vulcan smile almost invisibly would make women just to fall over him. And that safety wall also enabled that other side to show, it gave him ability to be mad at his Officer as hell, to just pout until something happens to lighten him up. He would never allow himself to act so childishly with anyone else. Even to Bones he would apologize in matters of minutes. His frustration with Spock could sometimes last for days. It wasn't sign of maturity but Spock's attempts to cross the distance in those moments would give him hidden sense of satisfaction which would in the end make him loosen up and get back to the game.
Reviews would be nice. When you work with characters like this you can't ever be too confident.
