No I haven't red most of the posts, but I've been having the same problem with a book I'm working on. Remember your Villain (even if he is a demon) is human too. Other then him being a demon, what makes him evil? Why has he chosen this path, what made him take it? Other then him getting taped in that world what motivates his actions?
Villains are Heroes in there own, they believe what they are doing is the right thing, and every villain needs a few things that make you feel for them. and all villains were probably good at one point. So write your Villain like he is the hero of his own story even though he is the bad guy.
That's coming a lot from some writing books i read but still a villain is the hero of there own story and normally it is often the true hero of your story that is there villain. When you have problems fitting things in a box, maybe something needs to be looked at from outside.
Hope this helps a little. smile