I think that Owen killed his father that night, since Durant said “i was here the night grandfather died”. Owen’s brother ( durant’s father) helped him with the corpse, Durant saw it all. Maybe Durant will trigger Owen enough with his imitations of Alexander (late emperor) for him to react violently and kill him too. If Durant dies, Owen becomes king/emperor and his daughter will be the heir to the throne.
Sooooo like DEAR DOOR