A Silent Killer

My name doesn't matter. It never has done and never will. If the enemy finds it out they can track me down to anywhere, my past, present or future. They will kill me or the others.
I never trust anyone and I make sure they don't trust me. Trust is a dangerous thing that can make or break you.
I'm 15 and I've already killed many....
My code name is Angel; but I couldn't be closer to the devil.