Sometimes Kirk would lie in bed and remember days he never lived. Years and years of unfamiliar faces and places he had never been would crowd in behind his eyes unbidden as he tried to sleep, insistent and persistent and impossible to ignore. And each and every one felt as real as the sheets beneath his back
Sometimes when the bridge was quiet Kirk found himself watching the science station, watching Spock, thinking idly about the taste of his skin or the soft curl of his mind against his - and then Kirk would catch himself and sigh, turn away.
Sometimes when Spock and Uhura ate together in the mess hall Kirk couldn't stop himself from staring. They were professional. They were discreet. But Kirk knew Spock better than he knew himself, now, and he could read every tiny tell, catch every subtle indication that they were a couple. He'd tell himself, See? This is how it is. This is how it's gonna be, and ignore the sick feeling twisting in his gut.
Sometimes Kirk would sit in front of his computer for hours when he should have been reading reports, or finishing his log, or in bed asleep. He would stare at his unfinished letter and maybe he would add a few lines, or delete a paragraph, but he would never actually write I think something went wrong with the mindmeld or I have these memories and I know they aren't mine or even I know you loved him and it's ruining my life.
Sometimes Kirk liked to imagine what would happen if he just walked up to Spock during alpha shift one day and slid their fingers together, if he whispered th'y'la in Spock's ear like the echoes in his head and pretended, for a moment, that what he felt was real. But his mind would betray him there as well, and even in Kirk's fantasies Spock would pull away in confusion, concern. Even in his fantasies Kirk was left with an ache in his chest and the knowledge that everything he felt was wrong, wrong, wrong.
Sometimes, in the middle of the day or during a mission when Kirk's mind was busy with the task at hand, he would catch Spock's eye and realize that he couldn't tell the difference between what feelings were real and which weren't, that he could no longer draw the line between which emotions were the result of the mindmeld and which had come from him. His breath would catch in his throat and his pulse would thump loudly in his ears, and for a moment Kirk would know nothing but blistering panic before pushing it aside, refocusing, thinking of something else.
Sometimes Kirk would remind himself that the feelings weren't real, were only figments from someone else's past that had no real meaning for him, for Spock. He could ignore them. He could keep them parceled away, separate from who he was.
Sometimes he believed himself, when he tried really hard.