Sounds very interesting. I might have trouble playing it since that mixture is new to me, but I'm certainly intrigued enough to try it. 

I'm going to get that this system of slavery has been around for at least hundreds of years. Do we want to go into the history of how it was instituted? I'm imagining a time when vampires were the evil creatures of lore, stalking the night and such, and then humanity discovered a toxin or something that helped them overcome them. Then the enslavement started as revenge and became a way of life. That's just the first theory that comes to mind, however.