[ Despite her familiarity with ghosts and monsters and corpses, the thought of possession makes something in her shudder. If that is the case with Lady Vannozza, they need to heal the affliction. ]

From my research, nothing like this is common. There was a war, years ago, when Lady Vannozza and her cousin Macaluso were both young and it took their parents. [ And war changes people; they grow too quickly. ] The ghosts mentioned plague sickness but that is incredibly rare, as well. Are you familiar with possession, young master?