Dick Grayson was fed up with Batman, that's true, but he was also tired, tired of always being treated like a kid, tired of keeping secrets, tired of fighting his inappropriate feeling for his best friend, just tired. At sixteen Dick left Batman, and he also left the team, he wanted to be his own hero, work by himself with out living under the shadow of the big bad bat, and he was also running, running from the feelings he wasn't supposed to have. Five years later he gets an offer, the team wants him to join, except they don't know he used to be Robin, and he's not about to tell them.