Will could have killed Dr. Lecter after he was released from prison. The hospital. Same thing.
He could have done it, his gun trained on Dr. Lecter's turned cheek. But he'd convinced himself that he had resources now, Jack and his justice. He didn't need to sacrifice himself to bring down Dr. Lecter.
After first, he didn't understand how Dr. Lecter had let such a situation come about. The gun could have been loaded. Will could have pulled the trigger. He could have blown Dr. Lecter's superior brains all over the inside of his superior fridge.
Then he realized just how predictable he was to Dr. Lecter. He couldn't have done a damn thing. That turned cheek. It was such obvious psychology.
If Dr. Lecter had any flaw (and of course he had many flaws, but what Will really meant was weakness), then it was ego. He was a man of infinite control, but he could become lost in self-congratulation at his own exquisite taste and cunning. Will saw it in retrospect; the look in Dr. Lecter's eyes as he presided over a dinner party or a crime scene (same thing.) It only ever lasted a second. But one second could last forever, at least to Will with his broken down clocks.
There was one such second, when they were standing in front of the fire, burning the notes, the clocks. Dr. Lecter was describing his memory palace.
Will couldn't imagine actually trying to remember things. He spent all his broken down seconds trying to forget.
"My palace is vast, even by medieval standards. The foyer is of Norman Chapel in Palermo. Severe, beautiful and timeless, with a single reminder of mortality: a skull, graven in the floor."
In that broken down second, Will could have killed Dr. Lecter. Pushed him into the fire. No predictability. No psychology. Justice, though not Jack's brand.
But Dr. Lecter's biggest weakness was ego. He had to be the smartest person in the room, even if he was the only one who knew it. And he always knew it. The best taste. Superior brains, in his head, in his fridge.
Dr. Lecter loved himself. And Will empathized with Dr. Lecter.
He couldn't have done a damn thing.