I've gotten quite a few emails since beginning the After the Reveal story arc (The Other Half and There's a Fine Line) questioning my "excessive" use of gay relationships amongst the vampires and elves. It was puzzling to me that, other than the insane amount of focus placed on first Kris and now Alicia to get pregnant, the sexual orientation of some of the tertiary characters was so upsetting to some readers. These stories were written for a (for want of a better term) porn site and I suppose I expected a bit more open-mindedness when it came to sexuality.
Yes, there is a category for gay males or females but I would never split the chapters into different categories as that makes it too damned hard to follow and find. I also wouldn't place the entire stories in the "gay" category as the underlying theme and motivating factor of both tales are the non-human aspects. The existence of these paranormal beings and how they've integrated into human society was the focus for The Other Half - not any of the characters' sexuality, primary or tertiary. The adjustment of a once-human girl to the discovery that she's not only the mate of a vampire but also more than human herself is the focus for There's a Fine Line. Again, the fact that there were a few same sex relationships in the story was just another glimpse of reality. I live in a small town (~35K) in the deep south and gay couples are fairly commonplace. The men catch more hell than the women though it's not always a walk in the park for anyone; however, it is reality as we know it today.
Johannes is bi-sexual with a preference for men though he prefers his female mate above all. He was a bi-sexual human and he turned into a bi-sexual vampire. Becoming a vampire didn't change who he was, simply gave him a bad case of the fangy nibbles. Francisco, too, was a bi-sexual human with little preference towards either sex though he preferred female Dominants. Devereux is a pure hedonist - he simply enjoys sex in all its many forms. He likes couples because that is the easiest way for him to experience a pleasurable sensory overload of sorts - hard male muscles, soft female curves, the welcome violation of a man's penis along with the welcoming heat of a woman's vagina are all a bit of heaven on earth for him.
I remember reading Anne Rice's vampire series not long after it first came out and, other than thinking that Louis was a bit of a whiny prick, one thing stood out to me. If you live forever, you will do one of two things: outgrow your prejudices or cling to them with vicious determination. I'd like to think that most people would see that love and beauty and the joy of a relationship isn't determined by your partner's genitals but by their hearts and minds and, if you believe in it, their souls. I'd think that most vampires (and elves and djinn and celestials) over the centuries would take some time for experimentation with a member of the same sex, or multiple partners, or different races because, eventually, the taboo will seem foolish or "human."
So, I suppose what I'm saying in this insanely long post is that, in a question about sexual preferences, most of my non-humans would simply answer "as often as possible." :)