Keeper of the Lost Cities

In Book 9.5, "Unraveled," while Keefe is in the human world, he encounters multiple instances of same-sex relationships. On pages 137-141, a jogger mentions having a "husband." Later, on pages 259-262, a waitress refers to her "wife." Keefe and Alvar discuss these human relationships, with Alvar stating, "It's really cool," and Keefe agreeing. This content has led to discussions among readers, including some Christian parents who express disappointment over the introduction of this theme later in the series.

In the first book, Sophie nearly gets hit by a car, and there are incidents of characters being knocked unconscious during a telepathy game. Later in the series, characters face more severe threats, including an extended kidnapping scene where young characters are drugged, bound, gagged, interrogated, and subjected to burns on their arms. There are also reports of fires in human cities that cause fatalities.

Sophie experiences "fluttery moments" and a "hummingbird mode" heartbeat when close to Keefe. The romance develops throughout the series, with Sophie and Keefe being frequently described holding hands, and a kiss between them is confirmed in "Stellarlune." While the early books are noted for minimal sex content, significant flirting is present throughout.

Multiple sources explicitly state that there is "no language" in the series. Plugged In's review mentions "Profanity & Violence" but then describes only the violence, implying profanity is not an issue. A parent reviewer for Book 9.5 also describes the series as "clean and amazing" regarding language, before noting other content changes.

Elves in the Lost Cities utilize abilities like telepathy (Sophie's primary talent) and telekinesis, with elves having used the latter to help humans build pyramids. The magic is described as being more scientific in nature, rather than involving wands, spells, or voodoo. While central to the plot, these powers are part of the inherent nature of the elven world and its species.

Several reviews explicitly state that there is "no sex" and "no language" in the series, and no mention of substance use. The content analysis indicates that such elements are absent from the narrative.

Sophie is exposed to dangerous situations from the first book, including nearly being hit by a car and being kidnapped. Later books feature more prolonged intense scenes, such as an extended kidnapping and interrogation where young characters are drugged, bound, gagged, and subjected to burns. The series also deals with themes of loss, bullying, and mental distress, described as "dark topics" handled tactfully but present.

Sophie often expresses resentment towards the Black Swan for withholding information from her, despite her eventual acceptance of her role. The characters frequently make decisions that go against established rules or direct orders from adult figures, for example, when Sophie ignores warnings and places herself in danger to find answers or save friends. The blurring lines between friend and enemy also lead Sophie to question whom to trust, often resulting in independent, sometimes rebellious, actions.

The narrative exists in a world populated by elves, dwarves, ogres, trolls, and other mythical creatures, where their inherent abilities function as 'magic' within a perceived scientific framework, without reference to God or traditional religious practices. One source notes that a prolonged immersion in secular books, even without explicit anti-Christian content, can convey a message that "there is no God or that God is irrelevant." The series promotes a worldview centered on the characters' abilities and actions in a non-Christian spiritual context.