Charley Sabini, who narrates Yep's novel of psychological realism, speaks in a believable voice that is simple and direct, but also probing in its focus on revealing details. Yep creates believable young adult characters not through slang or dated allusions to teen culture, but through a direct style and straightforward diction that nonetheless reveal sensitivity, liveliness, and curiosity. Charley is perceived by his peers as rational and self-controlled—perhaps too much so, according to his girlfriend, Chris. These qualities come across in his narrative style, which contains an analytical distance one would expect from such a character.

More noteworthy, perhaps, than the realism of the voices of Yep's characters is the way Kind Hearts and Gentle Monsters is meaningfully built around a central symbol and its variations. The idea of monsters announced in the title is woven carefully throughout the book. What is monstrous is...