The Princess and the Page by Christina Farley

A dark secret lurks in Keira's family. She comes from a long line of Word Weavers who bring their stories to life when they use a magical pen. But Keira's mom is unable to face the truth of the family's history because the Word Weavers have been hunted for generations for their power. And so, she forbids Keira to write. Oblivious to the family's secret ability, and angry at her mom's rule of no fictional writing, Keira discovers her grandma's Word Weaver pen and uses it to write a story for the Girls' World fairy tale contest, believing it will bring her good luck. But when Keira decides to have her fairy tale reflect her family's imperfect life, and has the princess in her story vanquished to a dark tower for eternity, she starts to wonder if anyone ever truly lives happily ever after.