Oh man, umm.... hmm. Since we don't have a plot really fleshed out yet it's hard for me to think of a good secret that won't potentially distract from the main story or be pointless. Just thinking out loud because it's gonna be a lame secret this early in the game... and because I'm not super creative ^^;
One of his secrets could be that his father (or some other close relative) is the leader of an eccentric religious group that seeks to obliterate lycans and werewolves. (So if he's asked to help get rid of them he'll just tuck his tail between his legs and run away.)