Quote Originally Posted by Ra1th View Post
It's an assumption, and its also widely accepted as the reason Datu recognized him. There is no other evidence for any other theory as to why Datu recognized him.

Angel was no longer frustrated with the chain of command, by about chapter 5 or 6. By then he'd accepted his role as second in command, and Michael as leader of the tower. You'd be hard pressed to find any evidence of him showing frustration with the chain of command after chapter 5
Shrugging it off once, a mistake, shrugging it off twice, with Datu and Scratch,He is trying to avoid recognition, even if he isn't the rat, Angel has a secret.