Personally, I'm against making Hexxat bisexual, mostly because there aren't enough lesbians (i.e. Chloe, Valerie(not out for BG2 yet), Sarah, and Auren (Only Nalia.).), but if you can make her a convincing bisexual then I really won't mind it as much. As for making Hexxat fit with more classic vampire lore. I'm totally for that, since a lot of people seem to compare Hexxat to Twilight characters.