I’ve seen a lot of discourse on Hannigram from Hannibal’s side, and I want to add my two cents from Will’s side: Hannibal is Will’s muse.
Will does not have effective barriers protecting the things that separate his “self” from the “outside”. He has to let some of it stain his psyche as long as he lives. This is why he doesn’t make eye-contact, doesn’t like socialising, doesn’t want to know the people around him and burden whatever pathos they come with.
And then the Chesapeake Ripper happens to him. He sees Cassie Boyle impaled on that decapitated antler head. The crows picking at her corpse, and the impact of this picture is so utterly traumatic and never ever seen before, that it manifests itself in the image of a feathered stag inside his mind.
Like ink staining his favourite shirt, it integrates itself into his psyche. The idea of who the Chesapeake Ripper is, his cruelty, his philosophies β Will instinctually understands. Yet this stag doesn’t harm him, but it’s always there. He can’t forget it. He forgets a lot of horrors, but he can’t let this stag go until he has to β when Hannibal cuts a piece of himself out of Will’s stomach.
Will even dreams of killing Hannibal using the stag, and he watches the stag die in the kitchen. Follows the stag around in the hospital, in Italy on the rail road. Even before meeting Hannibal’s true self, Will attaches himself to Hannibal through Cassie Boyle. And when he kills Randall and the prisoner in Castle Lecter, his tableus are inspired by the Chesapeake Ripper. When he kills Dolarhyde, he mimics Hannibal gutting him. Not anyone else, but only Hannibal.
It is poetic that Hannibal’s influence on Will isn’t entirely direct or related to psychic driving; but from the very first day, Hannibal has been someone unforgettable to Will, traumatic, permenant, comforting, and someone who has inspired Will when he performs nefarious acts in the name of righteous justice.