By Gail Carson Levine
A Cinderella retelling where the heroine is cursed to obey every order she's given, and spends the whole book fighting to be free of it.
At her birth, a foolish fairy 'gifts' Ella with obedience: she must do whatever anyone tells her to. It sounds harmless until you realize anyone can command her to do anything. When her mother dies and her father remarries a cruel woman with two spiteful daughters, Ella sets off on a real quest to find the fairy and break the curse before someone uses it to destroy her.
For the older princess lover ready for a full novel, this is the crown jewel: a Newbery Honor book that takes Cinderella and gives her grit, a sharp sense of humor, and a genuine problem to solve. Ella is nobody's victim, she schemes and jokes and fights her curse the whole way, and the romance with Prince Char is the swoony, slow-building kind. It's the natural graduation from picture-book princesses to a story with real stakes and a real heart.