Actually I'm thinking of giving him some kind of particle aura when he makes his appearance which will change color after his mood. Changing the eye-color is a good idea though. I think I'll do that as well.
I started out with a white eye but I think it's better with the current one. The advantage with an actual eye is that he can pinpoint his victim with his stare. Uhm, don't know if that makes any sense at all...:/