Pen To Paper

So I am working on a new story thing. I have the characters in mind and the basic relationships between them, and I know how I want one scene at the very end to go, but I'm not really sure about the antagonist. I'm not sure why he's there and what he's doing. I mean, sure there's the nebulous destroy the world/rule the world thing, but that just feels done to death. The whole thing is kinda' frustrating because the story isn't really going to go anywhere until the conflict gets figured out. I'm pulling from a bunch of different shapeshifter mythologies, and tossing in something I came up with. So hell, I may just make him a psuedo vampire, but that seems so boring. Which, make it interesting, find a new way to make it work, yeah yeah yeah. So off to look up various mythologies and try to figure out what my macguffin is. Whee!