@HotGirlShi She's a little kid. She's biologically programmed to try to rely on adults to survive. You think she would rather go back to foraging poisonous berries and eating mice, living in a cold, ruined mansion, than sleep in the warm bed, eat delicious warm meals, cookies, and chocolate? Besides, she seems to possess some of her mother's memories. Her mother loved the emperor in those memories, so there's that as well.
Besides, she doesn't act like family with him in the first place. She's afraid of him, can't really trust him, and wants to keep some distance as seen in this chapter.