Concept: deniable asset. This could be a lot of things, but basically, he's an Unaligned (or Apostate, or Ghost Wolf, or whatever) who has a lot of connections and allies within the different Covenants/Orders/whatever. What does he do? The dirty work none of them want their name getting tied back to. He's good enough at it to cover his tracks so there's never any real proof, but he's not good enough at it that he goes unsuspected because, well... everyone's "hired" him to do some of their dirty work. He avoids assassination because even though he isn't a formal member of any Order/Covenant/whatever, he has their protection (to a degree) because to not give him that protection, to allow his assassination, is to end the possibility of repeat business, and well... you know... he's good at his espionage shit.
