YA fantasy is a subgenre of young adult literature, a broad mode of fiction that addresses the concerns of teens and adolescents. Defining YA literature is, as scholar Michael Cart notes, a difficult prospect, due to the massive scope of what may be considered “young adult” and the ever-changing nature of the term “literature” (Cart, Michael. “The Value of Young Adult Literature.” Young Adult Library Services Association [YALSA], 2008). The boundaries between YA, children’s books, middle grade books, and the newer category of new adult books (which looks at protagonists aged 18-29) are often unclear. YA author Courtney Summers, whose books often feature protagonists who are 18-20 but remain frequently characterized as YA, refers to this as “crossover YA” (Summers, Courtney. “Who Is a ‘Crossover’ Book For?” Publishers Weekly, 2020). The Shadows Between Us, which features a romance between an 18-year-old heroine and a 19-year-old hero, but which is still marketed as YA, fits into this category.

YA fantasy, which has proliferated in popularity in the late-20th and 21st centuries (following the massive commercial success of J. K. Rowling’s Harry Potter series, among others), tracks adolescent stories in various ways, including narratives that contain magical elements in real-world settings and narratives set in fantastical worlds.