Jim is hopelessly in love with Spock, but he's in a seemingly committed relationship with Uhura. So Jim begins a relationship with Spock Prime, who is trying to re-capture his relationship with the Kirk of his universe.
Can end happy or sad, Kirk can end up with whoever/no one, author's choice.
Bonus points if: 1) Everyone's motives for being in their relationship (Kirk/Spock, Kirk/Spock Prime, Spock/Uhura, etc.) is revealed in a really over-the-top dramatic way (in public/with lots of eye-witnesses).
2) Kirk cries at somepoint (can be about anything).
3) Sexy-times are had (Jim-Bottom).
Characters: McCoy, Uhura