Adam is a popular, cheerful high school senior with ADHD who lives with his mother, Catherine. He acts as the energetic center of his friend group, frequently coordinating social outings and calming down his more volatile peers. He serves as an aide to the school psychologist and uses this position to reach out to his former foster brother, Julian, noticing that the younger boy is struggling socially and emotionally.

Julian is a timid high school freshman who recently lost his parents and now lives with his strict uncle, Russell. He suffers from severe social anxiety, wears ill-fitting clothes, and struggles academically due to his slow verbal processing and poor handwriting. To cope with his harsh reality and frequent bullying, he retreats into his imagination and relies heavily on reading Elian Mariner fantasy books.

Russell is Julian's uncle and legal guardian, having taken custody of the boy following the death of Julian's parents. He maintains an immaculately tidy house but enforces strict, isolating rules, such as forbidding Julian from having friends over or interacting with others. He presents himself as a disciplined, orderly guardian to the outside world while maintaining intense, abusive control over his nephew's life inside their home.

Charlie is a tall, physically fit high school senior and one of Adam's closest friends. He comes from a large, chaotic family with tight finances, which often leaves him feeling frustrated and complaining about his circumstances. He is blunt, prone to scowling, and frequently questions why Adam insists on bringing the awkward freshman, Julian, around their senior friend group.

Emerald is a poised, highly intelligent senior who looks like a 1950s Hollywood starlet and is a childhood friend of Adam's. She often hosts friends at her house because her mother is frequently away spending time with a boyfriend. Though she projects a stoic, unbreakable exterior to her peers, she hides a softer, more vulnerable side from public view.

Catherine is Adam's fiercely protective mother and a former social worker. She previously fostered Julian for several months after his parents died and still carries deep maternal affection for the boy. She is known for aggressively advocating for her son when she feels the school system fails him.

Dr. Whitlock is the high school psychologist who meets with students struggling academically and socially. Because Julian constantly skips his appointments with her, she recruits Adam to act as her aide, hoping Adam's friendly presence will encourage the anxious freshman to attend his counseling sessions.

Camila is a high school senior and part of Adam's close-knit circle of friends. She is outgoing, confident, and sometimes bossy, frequently initiating games of Truth or Dare in the cafeteria. She occasionally causes friction within the friend group through her bold and impulsive actions.

Jared is a high school freshman who has been bullying Julian since they were young children together. He is lonely and aggressive, frequently mocking Julian during their Child Development class and on the school bus to get laughs from other students.

Miss West is Julian's Physical Science teacher who is notorious for her harsh grading and volatile classroom behavior. She publicly announces students' low test scores and snaps at anyone who disrupts her lessons, hiding a deep personal grief behind her bitter teaching style.

Jesse is a drummer in the high school band and a laid-back member of Adam's senior friend group. He often recommends obscure concerts to his friends and participates heavily in their cafeteria games and weekend hangouts.

Allison is Charlie's on-and-off girlfriend and a regular part of the senior friend group. She displays a motherly concern for her friends, quickly rushing to help when Adam twists his ankle in the hallway.

Matt is Camila's twin brother and a part of Adam's extended circle of friends. He attends social gatherings with the group and occasionally helps with tasks requiring extra manpower.

Kristin is a student in Julian's Child Development and Physical Science classes. She is openly hostile toward Julian, excluding him from group work to protect her grades and openly mocking his social isolation to other classmates.

Miss Carlisle is the Child Development teacher at the high school. She assigns the students electronic baby dolls to care for and occasionally has to discipline students like Jared who disrupt her class.

Mr. Pearce is the high school principal. He is known for turning up the cafeteria air conditioning to extreme levels based on academic studies, and he handles serious disciplinary and truancy issues within the school.