I like that her actions naturally affected the outcome in both timelines:
-When she pestered the prince time and again, he was annoyed. But the moment she stops doing it, it suddenly picks his interest. Typical gain-loss effect.
-When she bullied her half-sister, it made everyone want to protect her, attracting the prince's attention. But now that she's just trying to keep her distance and be strict, but fair, Maryjun probably sees her as the "cool, reliable older sister". No wonder she's clinging to her.