for example in a story i'm writing, there is a character named Revenge who's main goal is to get revenge. Is there a single word for that?
A modern term is aptonym. It is a play on “apt” (appropriate) and the “-onym” root for name. It is usually for jobs or qualities, not just personalities. Like a person named John Cooke who is a chef, or Usain Bolt is the fastest sprinter.