Dante and Virgil are now in the 6th Circle of Hell, the round of the Heretics. They pass a graveyard and and open tomb. Farinata, a partisan on the opposing side of the Florentine civil war, stands into view and starts trading insults with Dante. Then another shade pops up. He is Cavalcante, father of Guido, a poet ex-friend of Dante’s whom Dante caused to be exiled from Florence, leading to Guido’s death. The sight of his betrayed friend’s Dad causes Dante to feel guilty. I’m not sure what this has to do with heresy.