Imagine if Hannibal is a python he would have sneaked into Will’s home and circle around him to sleep in S1 and S2, and also when he tries to calm Will down from seizure by giving him python-hugs.
Then in Florence he was really heartbroken and in his desperation he would have swallowed Will whole, then when he’s hiding out in a corner waiting for digestion that was when the overwhelming sadness of not having Will alive on the earth really hits him.
So python Hannibal got really depressed and that in turn affected his digestive system resulting in indigestion and ultimate death (as a doctor he knows that he should have performed surgery to extract Will’s body out and eat something digestible but he couldn’t stand the thought of being separated from Will).
And Chiyoh buried Hannibal (alongside Will in his tummy) together beside Micha.