Perhaps it was his ability as an actor or it's the talents of the devil, but if you zoom in past what appears to be a smirk or "pleasant" expression, his eyes reveal something different: they are lifeless and looking in two different directions. It's like his left eye is deceptively fooling and distracting you while his right eye is studying you as a potential victim. How unquenchable was his blood lust? How many deaths is he responsible for?