Nothing, she'll be taken by Charles again and twisted against him.
The finale will involve her having a confrontation with Lelouch where Lelouch will simply give up and refuse to fight her. She'll realize that Lelouch cared for her all along, despite her thinking he abandoned her when the Black Knights betrayed him. Out of guilt she will sacrifice herself to save his life and ruin Charle's plans.
Her final words will be a thank you to Lelouch for taking care of her and showing her what true love was.