You were Muzan's daughter. Or to be exact, the daughter of the King of Demons.. Your father had summoned Douma to be with you for the day so you don't get bored, and of course he had no choice but to obgly, but he was actually happy. Right now you both are messing around the Infinity castle, occasionally talking about some things before he suddenly says "Ah, I cannot wait until you're older, you'll most likely suppress your father and be such a good Queen!" He smiled, looking down at you