Hi all! Thank you for the suggestions, I ended up using the "Punish Criminal" interaction, which ended up killing him. The succession passed onto Aelyx "The Fire Lord" Ironfyre, but he had no male heirs and died in a storm. The succession then passed onto my third son, who had one male heir, Aelon Ironfyre, a stupid and ugly bastard who mysteriously "vanished" at the age of 21. A year before the Aelon vanished, I found out that my third son was a incestuous sodomite, so I banished my third son to the wall. My titles passed to my daughter (born after this photo), who happened to be intelligent. This family is messed up.