I think you have to get lucky with a specific rune, I did manage to turn back at some point after repeated attempts. I do agree though, they do have SOME semblance of personality, as in Mark (the taur I think) seems to be more flirty and playful, and the Kangaroo seems to be more studious, but then when we actually get tf'd...They all act the same, more or less.
I won't lie, I like asshole characters in this situation because the game is basically a battle of wills between your character wanting to return/remain and them, but there should most definitely still be variation