If someone is possessed I would guess it is Kelmomas. He has an interior voice that guides him. He is focused on his desire for his mother's affection on one hand and the utter destruction of everybody and everything else on the other. Sounds like demon like behavior to me. Inrilatas notes that Kelmomas is singularly responsible for the meeting with Maithanet, the overall isolation of Esmi (driving Mimara away, killing Sami, creating the conditions for Inrilatas to be killed), the Yatwer civil war (through killing Sharacinth), and as Inrilatas notes, "He [Kelmomas] is not what he seems, Uncle."