The Problem with an Insane Character

I've been hard at work on a Manga to compete with a friend of mine in making one. It gives me some time to practice drawing too. So I thought I'd 100% wing it and just make a story on the spot in five seconds. I thought hey what the heck, challenge myself; break some barriers. I've gone a route I haven't tried before and I see why I hadn't before. My main character is one Vampire named Vayne who is my first balls out off the wall protagonist. Vayne is a hemomancer and does a lot of nasty things with blood and enjoys causing pain. He's fast, loose, and fun as far as a protagonist goes but at the same time he's hard to contain. I realize that Vayne's involvement in whatever plot I can set him in DOESN'T EVEN MATTER.

There's no ally or villain for someone who just wants to watch the world burn now is there? And it's been boiling my blood as of recent when I'm trying to come up with a decent enough plot for him to work with.

Another huge problem is the fact that he's completely one dimensional when it comes to character development. He's kinda murder murder murder kill kill kill and I like that. It's gonna be really fun to watch him work his insanity blood magic but at the same time it seems like we're looking through a very small keyhole into a pitch black room.

I'm starting to think that this type of character isn't my thing. I really like badasses as a character archetype but I'm a huge fan of character development. My huge problem with Vayne as a character is the fact that he's already at wits end and really doesn't have much room to develop from the get go.

Hmmm.... -_-