Earwig and the Witch - Diana Wynne Jones - Bog

Her name is Earwig, and she has been at the orphanage ever since she was a baby. That's how she likes it. She has a best friend, Custard, and everyone does exactly what Earwig wants. She never wants to leave, so she makes sure that no one ever picks her. But one day, a very strange couple adopts her and takes her home to Thirteen Lime Avenue. They try to make themselves look ordinary. But they are not ordinary, not in the least. There is a lot of magic brewing at Thirteen Lime Avenue. And Earwig just might discover that she likes it.