Blast is a blot, living entities formed entirely out of ink, with a few exceptions here and there, hence the running shoes and bomb head. Nobody really knows where blots come from or how they're formed, Blast being one of the most puzzling of them all. Having a head filled 95% with gunpowder has left Blast a little... not all there, but it's also given him quite an "explosive" personality. He may be a danger to himself and everyone around him, but he's got such a heart of gold that we just can't reject him. You'll just have to get used to the smell of flames and oil... Actually maybe not, he's very easily startled...