I'm glad you appreciate it and actually take the time to respond to comments, it's a rare sight these days! I believe that surely, if Markus managed to push Exit to the point where she wouldn't hesitate to let him have his way with her in one of the endings, then oral wouldn't be out of the question! After all, from what I've noticed, Exit has a hard time ignoring her own libido, and therefore can eventually give in to her captor if he uses this to his advantage!
She also appears to lose her confidence and smugness as Markus gets more intimate, and since the wide variety of endings also ultimately allow for a wide variety of states of mind for Exit, I'd imagine one where Markus would get bitten (if he didn't play his cards right) and once where he wouldn't (if he did) wouldn't be completely odd to see.
On a side note, I am glad to see fellow roleplayers making games, it almost always guarantees very good writing, which is clearly the case here!