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In TWOTL, we see Will & Reba talk about what happened with Francis Dolarhyde.
"W: In the end, he couldn't kill you, and couldn't watch you die.
R: I drew a freak.
W: You didn't draw a freak. You drew a man, with a freak on his back. There is nothing wrong with you.
R: I know there's nothing wrong with me. In making friends I try to be wary of people who foster dependency and feed on it. I've been with a few. The blind attract them.
W: Not just the blind."
See? "In the end, he couldn't kill you, and couldn't watch you die", and that's true about Hannibal & Will.
The dialogue between Reba & Will reflects how Will used to see himself/his relationship with Hannibal. It reminds us that Will used to be wary, too. Better to be alone than in bad company. Before knowing Hannibal, Will was alone most of the time, and ofc you can choose to be alone because you enjoy it, but I don't think the way Will isolated was entirely joyful. He did it to protect himself. Because he knows that the very way he sees the world can attract people who are dangerous to him, can attract people who "foster codependency". He's seen it before, his "uniqueness" makes him vulnerable.
And for a moment, Will genuinely believed Hannibal was a freak. Once he accepted his true nature, accepted to adapt, evolve, become, once he gave in to his real self, he was able to be at peace with who he is ("There's nothing wrong with you") and with who Hannibal is ("You drew a man, with a freak on his back."). He humanizes Francis, in the same way he humanizes Hannibal.
Also, side note, but the "Not just the blind." line could be a way to refer to Will's empathy. He does see, he sees a lot, he sees too much. And that, too, attracts dangerous people.
In a way, Will and Reba are very much alike, because they were both able to see beyond what's visible, to get to know the person they love. Reba's blindness allowed her to see past Francis' physical appearance which he was insecure about, making him feel seen in a way he craved, feel loved for who he was, just like Will's empathy allowed him to see the art in Hannibal's murders, allowed him to sneak a peek behind the person suit and access who Hannibal truly was.
Later, Will & Francis talk:
And this resonates with Hannigram, too. Francis chose to only share a little, "in a way she could survive". Hannigram didn't. They both let themselves be seen, be known. They both changed the other, and got changed by the other, whether they wanted to or not. "I chose not to change her," said Francis, and I'm not sure neither Will nor Hannibal could have chosen not to change each other. They belong to each other so deeply that they actually don't want to trick the monster inside themselves to let the other survive.
"F: I would like to share.
W: You shared with Reba.
F: I shared with Reba a little, in a way she could survive.
W: You didn't change her.
F: I choose not to change her."
They will change each other so thoroughly, that whatever will come out of their mutual transformation, isn't Will & Hannibal, as separate beings, anymore. They are one. They've consumed each other to the point that survival doesn't matter. They embrace their own nature and each other's nature so entirely, that being together surpasses the mere fact of being alive. Being loved is being changed, and they got changed in the most complete way.