The Headmaster's Daughter Book 0: The Invisible Girl

Anastasia Dumbledore lives in the back room of the Headmaster's suite of Hogwarts School of Witchcraft and Wizardry. Of course, no one knows that except for her grandfather, Albus Dumbledore, a select few Hogwarts faculty, and a couple of house elves. At ten years old, she is quite tired of living in secrecy and is ready to explore the world, much to her grandfather's chagrin.