Books and Adelaide are inseparable. Her gifts from her Fairy Godmother was a love of reading and a book satchel that summons any book she wants to read. She's fourteen years old, and Kimberley is her best friend. She summons plant books for Kimberley. Kimberley keeps her from running into anything while she's walking and reading at the same time - which is often.
She's not a very important character for book 2, but she'll be more important later on.