You know few things delight me as much as Sebastian being hurt. Please pepper him full of bullets, yes good.
Really, I think it should be up to you whether or not he bites her. I'm up for it, for the record! Threeway threads can be a bit difficult, but if someone's up for it, maybe the hunter arrives, Sebastian immediately runs off (for this AU, he will actually be aware of that he's not unbeatable. wow, amazing) and then it continues as a thread just between the hunter and Constance?