Prisoner? No! I Want The Crown!

Blair is the real princess of Daxon. Lily was switched with her as a child and has lived in her place ever since, and Blair spent the twenty years that followed in a dungeon in an enemy kingdom. She comes back to the palace with no belief left in anything but power. She starts by taking the general who is engaged to Lily. At the Tiance Tournament she shows the court what she can do, and when black magic traps are laid for her she breaks them. The emperor carries guilt over what was done to her, and she puts it to use, breaking the alliance between the Empress and the Empress Dowager and then bringing the prince's betrayal into the open. Through all of it the general lets himself be used as her pawn and keeps her protected while the palace fills up with plots.