I believe it was Freud who speculated that everyone in our dreams is a representation of some part of ourselves. I believe that writing and acting are a lot like that sometimes. For an actor, they get the chance for a little while to become the character they play. They get to see what they see, feel what they feel. Or in some cases, the character becomes the actor.
For me, writing is like that. In every book, to a certain extent, the main character gets to become me for a little while. The book I'm working on now (Diary of an Incubus, which I'm close to finishing) is the first time I've ever had a main character who isn't me. She started out as me, or so I thought. As a matter of fact, this novel began as therapy. But through the course of the book she has grown, changed, and developed into someone else.
I like her, that's not the problem. Really, there is no problem. It's just very interesting who I have become in this story ... or who has become me. At the moment I am a vampire, a very bad vampire and I'm enjoying it very much. I get to frighten people just because it turns me on. I get to flash fangs in a dark night club just to hear the heroine gasp ... and I like it. There's no telling what I'll do next, but it's so much more fun than being the hero.