Please no non-con and no death-by-suffocation if the non-human character is a Lanius, but I'd love to read something about a human character getting intimate with a crewmember from one of the other races. It doesn't have to be smut, romance is sweet too, but a focus on the differences between them and how cool/weird they are would be good.

Maybe the rest of the crew died and it's just the two of them alone together, fighting a losing battle in the name of the Federation. Maybe they're the teleporter crew, and all the frantic battle-lust has been building up between them each time they beam over, not knowing if it will be the last time. Maybe a Zoltan always rushes to help their Human friend even though they're weak as heck and it messes up the reactor every time. And so on and so on.

Oh, no, I have so many ideas now!