One of four narrators, Sylv, Hispanic and a high school senior, lives on a farm with her brother, Tomas, and grandparents, where Sylv cares for her sick mother. Autumn’s girlfriend and an over-achiever, Sylv has been accepted to Brown University next year, and feels guilty about keeping this fact from Autumn. Throughout the book, Sylv is characterized as a girl who goes against conventions. While fear causes Sylv to hesitate in the minutes following the shooting, her courage, empathy, and insight surface as the novel progresses. By the end, Sylv's love for Autumn inspires her to transform her fear into bravery, as her attempts to rush Tyler onstage are squashed when a student tackles her. Later, she attempts to confront Tyler a second time.

Another one of the four narrators, Autumn hopes to attend Juilliard next year and follow after her mother, who was principal dancer in the Royal Ballet, but Autumn's dreams shatter when her brother Tyler shoots Autumn in the knee. Autumn plays a central role in This Is Where It Ends, as countless times her memories of better times with Tyler create empathy for the shooter, as well as characterize Tyler as capable of beautiful actions. Like the other narrators, Autumn’s fear in the minutes following the shooting turns into courageous action as she confronts Tyler onstage and later sneaks away to find Tyler.