Hi, You Were My Husband in Another Life, Professor

Um, hi. I'm Jim. Jim Kirk. You don't know me, but I know you. Well, sort of. It's a long story. All of this started when I… Actually, no, it started when my mom got it into her head that… well, it's kind of complicated. Long story short, I accidentally ended up in another universe and... Look, I know it sounds crazy, but in that universe, we—the other me and you—are married and you're the crown prince of Vulcan Kingdom. It does sound crazy, I know. Fuck, I don't even know why I'm doing this. I don't really know you. Hell, I'm not even sure I want to know you. It's not like I think you and me… I'm just curious, I guess. You'll probably ignore me anyway; I know I would if I were a Vulcan and got a call like that from some stranger. Fuck it, it was a stupid idea. Bye, Spock.
[18-year-old Jim ends up in Once Upon a Time's universe. When he gets back, Jim's curiosity gets the better of him. And then things become complicated. Academy AU.]