I don't think he's gonna end up with anyone. Ashe doesn't fit well with Vaan at all. Ashe is all, "grrr, I'm so hardcore! Resistence! AVENGE THE DEAD!" while Vaan is all, "hmm? What's going on over here? Pie?" And Vaan and Penelo have too much of a brother-sister relationship. If something happens between them I'll be all, "ew". And Fran, no way, not gonna happen.