Jim woke with a shout. He had been too exhausted to notice the dreams, at first, but after the second night running when scenes from lives that he had never lived, but were somehow inexplicably him traced their way across his mind, he had it figured out. He had collared McCoy for a quiet chat about potential side effects of a Vulcan mind-meld.
"Hypothetical, my ass," McCoy had snorted. "Which one did you do it with, the sarcastic one or the wrinkly one?"
Jim hadn't dignified that with an answer. In the silence of his quarters, he sat up, breath slowing as the real world, his real world, formed back around him.