Ah, I get it.
She's trying to overall be the one in control and the one with the power so that by making her brother the emperor, he will understand that his power came from her. That he owes it to her and that he can't simply just toss her away. She is trying to change him by expressing love and affection to him, but she is also manipulating him and events so that he is also dependent on her and needs her to become emperor.
In a way, she's very much reversing the roles that they had in the last life.