The Keeper of the Lost Cities series is set in a fantasy world where elves, gnomes, dwarves, goblins, and trolls exist apart from humans. In this world, what humans consider myths and legends are real, including magical creatures and supernatural powers. It can be characterized as “middle” fantasy, meaning that it has its own magical system but exists alongside the human world.

The series has many similarities to the Harry Potter series. Both are middle fantasy and follow a “chosen one” narrative trope: In the Keeper series, the protagonist, Sophie Foster, has exceptional gifts and is poised to save the elvin world. Both series begin when their protagonists are at a similar age (Sophie is 12, and Harry is 11) and grow with them from book to book. In addition, both include a school setting: Harry and his friends at Hogwarts, Sophie and hers at Foxfire, where they learn how to use their special abilities.

As in Harry Potter, the Keeper characters’ names provide insight into their identities and roles in the story. For example, “Sophie” comes from the Greek “Sophia,” meaning wisdom. Ruewen, the surname of Sophie’s elvin parents, who grieve the loss of their daughter, incorporates “rue” and when said in full sounds like “ruin.