Even to this, Vampires are not completely evil (pure evil pops up much later in this series). They are a bit self-serving and brutal, yes, but their unofficial spokeswoman (or spokesvamp...or something) Elizabeth wishes to see her kind put in the same regard as Dark Ones. There is a bit of an unspoken hierarchy in the Immortal world, and the concerns of Vampires and Werewolves (their counterparts are the Night Wolves) aren't too high on the totem pole of power. Elizabeth hopes to change that...by any means.
Elizabeth's plan developed purely by accident on my part. I knew she would grow into an important role, I just didn't know how important. This was another example of a character I created taking my pen and running with it. She is not as fleshed out as the twins (whom she meets early in the story), but her blinding ambition and sense of destiny was all that was needed to begin the process of turning her into a force to be reckoned with. Trust me, Forbidden Children is just the tip of the iceberg for her.