The knight

It’s the knight, who tells Nastagio that he has been in the same predicament as Nastagio is now: being in love with a cruel woman. He tells him that he is a spirit; like Nastagio, he himself became suicidal at the pain of his unrequited love, but he carried out his plan to end his life. This resulted in divine punishment: the knight has to use the same rapier he killed himself with to kill the woman he loved. This song and dance will be carried out until infinity: the knight kills the woman by stabbing her through her heart and feeds her organs to the dogs, after which the woman will magically wake up and run away, only for the knight and dogs to chase and kill her again.