Some readers and parents at times object to legends promoted as a coherent system of beliefs; in this novel and others in the series the references are subordinate to the story itself. Cooper has imaginatively adapted all of the myths and legends she uses for her own artistic purposes.

The novel contains no graphic violence. The Drew children are threatened in certain scenes but are never physically harmed, and the threats come only from those people who are of the Dark.

Evil is real, tangible, and often not immediately recognizable in Cooper's world, and good must constantly struggle to keep it in check. Cooper is realistic about the difficulties, but optimistic about the outcome. She never develops the concepts of good and evil in any theological way, so readers of all religious persuasions should have no problems with this fundamental conflict in the story.