Something the Hannibal television show does phenomenally, that the books and movies don’t really do at all, is showcase how well he actually blends in.
In the Thomas Harris works, every scene that Doctor Lecter is in manages to make it very clear that he’s dangerous, and everyone else is basically Damocles without being aware of the blade. He’s unsettling even when he’s charming, and the audience is always aware that he is the lion in the room. We can see the swords dangling by the hair over every other character.
But in the show, Hannibal is just a guy, maybe pretentious and nerdy, but charming and kind for the most part. We are taken in with him, just like the other characters. Then, when he does lash out, moving like the predator he is, we’re left absolutely shook, almost ashamed that for a moment we forgot who he is. In the next scene, he’s as soft and charming as ever, and the deception begins again. We slowly fall under the spell again, because he’s just that good. We experience what the characters do, even though we’re granted the behind the scenes knowledge that he’s the villain of the story.