Evan is a high school senior with severe social anxiety who lives with his single mother. He relies on medication and therapy assignments, such as writing letters to himself, to manage his daily life. Following a summer where he broke his arm while working as a park ranger apprentice, he struggles to engage with his peers and feels largely invisible at his school. His life grows complicated when one of his private therapy letters falls into the hands of a volatile classmate.

Connor is a volatile high school outcast known for wearing dark clothing and causing disturbances. He struggles with substance abuse and anger, frequently clashing with his parents and his sister. Despite his intimidating exterior and reputation for aggressive outbursts, he desperately wants to be heard and understood by the people around him.

Zoe is a high school musician who plays guitar in the jazz band and performs at local open mics. She maintains an independent spirit and tries to distance herself from her family's domestic stress. Her relationship with her brother is highly strained, as she resents his cruel behavior and the disproportionate attention his problems demand from their parents.

Cynthia is Connor and Zoe's mother. She is deeply invested in trying to help her son, frequently pursuing various treatments and interventions to manage his behavior. She takes a patient and forgiving approach to parenting, though she struggles to look past her son's immediate behavioral problems to see his underlying potential.

Larry is Connor and Zoe's father. He works long hours as a lawyer and spends relatively little time at home with his family. He employs a rigid, strict approach to parenting his son, which often creates friction and drives a wedge between him and his children.

Heidi is Evan's mother, raising him alone after her ex-husband moved to Colorado to start a new family. She works grueling hours as a nurse's aide while taking night classes to improve their financial situation. She loves her son and actively monitors his mental health, though her busy schedule leaves her physically absent from the house much of the time.

Jared is a high school student who insists he is only a "family friend" to Evan because their mothers know each other through a real estate connection. He hides his own insecurities behind sarcastic jokes and trendy outfits. He possesses significant technical skills but often sits alone in the cafeteria.

Alana is a highly driven high school senior who participates in numerous student organizations and prestigious internships. She moves through the school with a massive backpack and a cheerful demeanor, actively seeking leadership roles. Despite her constant participation in school activities, she shares a feeling of social invisibility with her quieter classmates.

Dr. Sherman is Evan's therapist. He attempts to help Evan manage his severe social anxiety by assigning him writing exercises designed to articulate and sort out his feelings.

Mrs. G is an elementary school teacher who taught both Connor and Evan in the second grade. She is central to a school rumor regarding a classroom incident, though the reality of her teaching methods involves patience and structured problem-solving.

Ranger Gus is the park ranger who supervised Evan's apprenticeship over the summer. He enforces park rules strictly, a quality that Evan quietly appreciates for the structure and boundary-setting it provides.