Waif is the fabled Elfgift of High Norland at the time that Charmain Baker begins to work in the Royal Library. As such, she is highly magical and has the abilities and knowledge to defend the King and the country. She can even change her size and gender to fit her needs.
When Waif first appears, Charmain Baker looks at her from a table. William Norland's voice asks her to be kind to Waif. She eventually comes with Charmain when she is going to the Royal Mansion to work as the librarian, in response to a letter from the King of High Norland. At the end of the book, it is revealed that Waif is the long-lost Elfgift and has been made pregnant by the cook's dog. William Norland also states that her puppies might inherit the Elfgift.