Disclaimer: I don't own Star Trek.
The James T. Kirk Touch
McCoy did not think Jim was hugged enough as a child. He noticed this, of course, because he was a doctor, and therefore had highly developed powers of observation, capable of deciphering the smallest movement, the slightest nuance. Also, because not two hours after they met, Jim gave him a back massage 'to help him get over the shuttle flight', and that night, when they were walking back to the hotel after they went to a bar and got only mildly tipsy, Jim sort of put his arm around McCoy's shoulders and sprawled, bonelessly, all over him, which McCoy might have attributed to the alcohol had Jim not done the same thing, time and time again, when perfectly sober.
Bunking with Jim – God, now there was something, as McCoy found out on their first offworld training mission at the Academy. Jim cuddled. Like a goddamned puppy. It didn't matter how many times McCoy pushed him away or woke him up, the result was always the same: give him two minutes to fall asleep and suddenly you'd have an arm over your stomach, a drooling mouth at your neck or on your shoulder, and long legs flung out over all sorts of uncomfortable places.
Resistance was futile. McCoy didn't even bother trying. It was just how Jim was, he couldn't help it. And when McCoy found himself patting his nurses on the back after long operations, ruffling his patients' hair during recovery, and, yes, hugging Jim back on a regular basis, he figured it had only been a matter of time before Jim's touchiness had infected him, and neither the nurses nor the patients (nor Jim, for that matter) seemed to mind.
And then they got the Enterprise. Hundreds of new people who didn't know James Kirk (and at least a few dozen who hadn't even heard of him). Nice, reserved, military sorts of people. Sulu, who believed in manly back-slaps but was otherwise stoic. Uhura, who was calm and cool and not particularly cuddly. Scotty, who, if he did get a bit more touchy sometimes, at least set up a still in Engineering. Chekov, who seemed to have had little social interaction with people beyond work and thus kept his hands to himself. And Spock, who was about as likely to cuddle as he was to jump on the conn and dance a jig. It was beautiful.
And then, one day after an away mission that left the away team in the sickbay, Sulu got out of surgery and clasped one of McCoy's hands in his. "Thanks, doc," he said, and squeezed.
McCoy told himself it was the drugs, and didn't mind.
And then, on his fourth divorce anniversary, Uhura walked into his office for no other purpose than to give him a hug.
Scotty, after managing to do something to the transporter that sounded too long and complicated for McCoy to understand, actually jumped on McCoy while laughing maniacally.
Chekov, on figuring out some equation that saved two ensigns stuck on an ice planet, grabbed McCoy's forearms with both hands and grinned until McCoy patted him on the head.
And one day, after a mission that went bad where McCoy lost a young lieutenant, Spock, very gravely, reached up and patted him on the shoulder.
That's what did it. Not only had Jim managed to infect the entire crew, he had contaminated the Vulcan. The Vulcan! It was an affront to all that was right and natural in the universe, but there was no help for it.
Jim had won.
That night, McCoy consoled himself with a bottle of bourbon and a trashy romance novel that Jim had recommended, and the next morning he steeled himself, walked up to the bridge, and gave Jim a half-hearted half hug.
If you couldn't beat them, you just had to suck it up and join them.