John Murphy | The 100
Murphy's coming in from 2x16, so he knows most of what happened in canon (except, of course, the stuff that happened after he left with Jaha). He's prickly and not a very nice person, so he's going to push away people who try to befriend him, even though it's what he needs most.
He's not sure what to think of this weird Supernatural stuff, either, so it'll be interesting to see how he does with that.
And he will be up for anything in the way of platonic/romantic relationships, although everything's going to take a while for him because you have to get past all the prickly layers of his onion. ;)