Sloane is a seventeen-year-old girl living in an oppressive society where teenage depression is criminalized and treated with forced memory erasure. She struggles to process her grief over her brother Brady's death while hiding her emotions from her parents and government monitors. She wants to protect her relationship with her boyfriend, James, fearing the authorities will flag them both as sick. Her ability to suppress her feelings is constantly tested by the restrictive world around her.

James is a seventeen-year-old boy with blond hair and blue eyes who relies heavily on his relationship with Sloane. He carries deep scars from his mother's abandonment and his best friend Brady's death, choosing to tattoo the names of lost loved ones on his arm so he never forgets them. He possesses a rebellious streak that draws the attention of government monitors. His primary motivation is keeping Sloane safe and maintaining a facade of normalcy.

Michael Realm is a teenage boy Sloane meets while undergoing treatment inside The Program. He bears a scar on his neck from a previous injury and spends his time playing a card game with other patients. He offers Sloane companionship and a listening ear in a highly controlled, terrifying medical environment. He harbors private information regarding how the facility operates.

Lacey is Sloane's childhood best friend, known prior to her treatment for her rebellious personality and unique dyed-hair aesthetic. Her parents surrender her to the authorities after finding a bottle of poison in her bedroom. When she returns to school as a "returner," her altered state and erased memories greatly shock her old friend group.

Brady is Sloane's older brother and James's best friend. His tragic death prior to the main events of the story leaves a lasting impact on his family and friends. The grief surrounding his loss bonds Sloane and James together but also puts them at risk of being flagged by the government's depression monitors.

Miller is a close friend to both Sloane and James, and Lacey's boyfriend prior to her treatment. He becomes deeply distressed and struggles to cope when he realizes Lacey has returned from The Program with absolutely no memory of him or their relationship. His emotional decline severely impacts James and Sloane.

Sloane's mother lives in intense fear of the teen suicide epidemic following the tragic loss of her son Brady. Her desperation to keep her surviving daughter safe causes her to place unwavering faith in the government's medical systems. She actively discourages Sloane from discussing the past or showing negative emotions, creating a tense home environment.

Sloane's father shares his wife's profound anxiety over the possibility of losing another child to the epidemic. He tries to protect Sloane from drawing the attention of government monitors but occasionally clashes with his wife over how to manage Sloane's mental health. He covers for Sloane when she has physical accidents to avoid suspicion.

Dr. Warren is a therapist working inside The Program. She conducts mandatory psychological sessions with patients, using a combination of talk therapy and colored pills to extract and eliminate specific memories. She maintains a calm, clinical demeanor while executing the government's coercive medical protocols.

Roger is a dark-haired handler employed at The Program. He uses his position of authority over vulnerable, memory-compromised patients to his advantage. He illicitly offers the teenagers special pills that supposedly preserve memories, demanding inappropriate favors in exchange for his contraband.

Kendra is a classmate of Sloane's who struggles to maintain the required facade of happiness. Handlers forcefully drag her out of the classroom during a daily wellness survey, demonstrating the immediate and violent consequences of showing emotional distress in public.

Dr. Francis is a doctor at The Program who firmly believes that the teenagers are suffering from a dangerous infection. He justifies the facility's lack of patient autonomy by insisting that a diseased mind cannot make proper health decisions, reflecting the institutional arrogance of the medical staff.

Tabitha is a patient inside The Program who suffers from permanent short-term memory loss after consuming a poison called QuikDeath. She repeatedly asks to join card games in the recreation room but never remembers the rules, prompting the other teenagers to turn her away.

Kevin is a government-assigned handler who monitors returners after they are discharged from The Program. He drives Sloane to school, ensures she integrates smoothly into society, and actively warns her against associating with people who might trigger her removed memories.

Anna is Michael Realm's sister who lives outside the direct confines of the medical facilities. She holds significant information regarding resistance efforts against the oppressive government and provides supplies to those looking to escape the system's reach.

Liam is a friend of Lacey's new boyfriend, Evan. As someone who has not gone through The Program, he displays a morbid curiosity and insensitivity regarding the memory erasure process, outright asking returners invasive questions about their trauma.

Derek is a teenage patient undergoing treatment in The Program. He spends his limited free time playing cards with Realm and Shep, finding small ways to pass the time in the highly restrictive medical environment.

Shep is another teenage patient assigned to The Program. He frequently socializes with Derek and Realm during their designated free periods, participating in card games to distract himself from the clinical surroundings.

Nurse Kell is a medical professional working at The Program. She manages the physical movement of the patients, escorts them to their mandatory therapy sessions, and acts as the enforcer for the doctors' medication orders.

Evan is a teenage boy who begins dating Lacey after she returns from her treatment at The Program. He socializes with the "returners" and brings his non-returner friends into their social circle, creating occasional social friction.

Ally is a teenage girl who arrives at The Program as a new patient. The medical staff immediately pressure her to integrate with the other teenagers and participate in the daily card games to establish artificial emotional connections.