Spoiler!
The truth is she literally cares for her brother and she wants him to become the heir of the family, and MC literally doesn't even understand anything about her, she's the only one who truly loves MC in the family, in the first timeline she sacrificed herself to the emperor to protect her country & people (the saintess also does the same, but this time MC changed her fate)
✕Meanwhile the Knight, well this MF is straight up a Simple, he deserves to die