Kristina is a 16-year-old honors student living a relatively stable, privileged life in Reno, Nevada. During a summer trip to visit her estranged father in Albuquerque, she develops an alter ego named "Bree" to express her repressed, rebellious desires. As Bree, she feels empowered to break rules, flirt, and experiment with drugs, beginning a dangerous relationship with crystal meth that threatens to consume her entire identity.

Marie is Kristina's hardworking, protective mother and a writer by profession. She has built a stable life for her children with her new husband, Scott, but struggles to connect with Kristina. Her strict, high-achieving expectations and deep distrust of her ex-husband inadvertently drive a wedge between her and her daughter.

Kristina's unnamed biological father is a man in his mid-forties working an off-the-books job at a bowling alley. Estranged from Kristina for eight years, he lives in a rundown apartment and maintains a permissive, neglectful parenting style. He struggles with his own addictions, creating an environment where Kristina is left largely unsupervised.

Adam is an improbably handsome teenager living in the same Albuquerque apartment complex as Kristina's father. Dealing with a troubled home life and family tragedy, he copes through substance use. He becomes Kristina's first love, introducing her to cigarettes, marijuana, and crystal meth while wrapping her in a manipulative, intoxicating romance.

Known as Reno High's "storied bad boy," Chase is a linebacker who crosses paths with Kristina upon her return to Nevada. Despite his rough reputation and involvement in the local party scene, he frequently surprises Kristina by quoting poetry and displaying a gentler, more respectful demeanor than she expects.

Brendan is a charming, conventionally good-looking lifeguard whom Kristina meets during a family outing. While his clean-cut appearance easily wins the approval of adults like Marie, his handsome exterior masks a deeply predatory nature that poses a severe threat to those around him.

Scott is Kristina's stepfather, a stern and heavy-handed man with high expectations. He works for a tech company and provides a comfortable, middle-class life for the family in Reno, though Kristina often feels alienated by his strict rules and continuous presence.

Leigh is Kristina's older sister, a beautiful college student exploring her own identity and coming out process. She cares deeply for Kristina, attempting to nurse her physical and emotional wounds and serving as a steady, pure source of affection in the family.

Jake is Kristina's young, red-haired half-brother. As the youngest member of the family, he represents the new life Marie has built with Scott, making Kristina occasionally feel like an outsider in her own home.

Lynx, whom Kristina privately nicknames "Lince," is a young woman living in Albuquerque. She is fiercely protective of her relationship with Adam and immediately views Kristina with suspicion, highlighting the competitive environment surrounding Adam.

Sarah has been Kristina's best friend since fourth grade. She represents the wholesome, predictable life Kristina lived before her summer trip, but struggles to understand the profound changes Kristina undergoes.

Trent is a high school classmate of Kristina's who faces bullying for coming out as gay. He is part of Kristina's old, reliable friend group alongside Sarah.

Robyn is Trent's sister and a high school cheerleader. Behind her popular, high-achieving exterior, she harbors secrets and copes with immense academic and social pressure by participating in the local party scene.

Albert is an elderly, complaining man who sits next to Kristina on her flight. Still mourning the death of his wife, his loneliness prompts Kristina to reflect on her own feelings of isolation and her expectations of love.