Bewitching by Alex Flinn, 2012 Harper Teen
After encouraging Kyle and Lindy to find internal attraction rather than superficial beauty Kendra moves to Florida where she meets Emma. Emma's mother remarried and his daughter is coming to stay. Emma's mother doesn't believe her new daughter could possibly try to ruin Emma's life and steal away her daddy.
Kendra befriends kind Emma at this new school. Throughout telling Emma's story and helping her deal with the step-sister drama, Kendra tells part of her story: all four-hundred plus years of it.
Though she wants to use her magic to help Emma, Kendra has experience with magic gone wrong and is afraid of helping her new friend with the same results. Emma and Kendra bond as normal teen girls over Emma's new boyfriend and her new step-sister trying to steal him.
As Kendra and Emma become closer friends Kendra tells the story of her failed attempts to help other friends in other lifetimes. Her past stories mirror Hansel & Gretel, The Little Mermaid, and The Princess and the Pea. Emma's story mirrors Cinderella as the two navigate high school and friendship in an ever-changing world.
Flinn retells the traditional fairytales wrapped in new settings. Romance and difficult families drive the plot while the friendships Kendra builds over and over give purpose to her continued existence and immortality. Teen readers will understand and enjoy Kendra's somewhat irreverent attitude balanced against Emma's more straitlaced tendencies.