Adam is a 15-year-old high school sophomore coping with OCD and anxiety. He splits his time between the homes of his divorced parents. His compulsions heavily involve counting, tapping patterns, and navigating thresholds, to the point where he cannot enter rooms without performing specific rituals. He feels a heavy responsibility to protect his loved ones and views himself as a protector or "Batman" to those around him.

Robyn is a high school junior recovering from her own mental health struggles. She chooses the alter ego "Robin" for group therapy. She shows an early interest in Catholicism, finding its rituals soothing, and she relies on Adam to teach her about the faith.

Carmella is Adam's mother and works as a nurse supervisor. Following her divorce, she struggles with severe hoarding, creating an overcrowded and stressful living environment. She often receives toxic, threatening letters that she asks Adam to keep secret from everyone else.

Sebastian is Adam's father, who divorced Carmella and remarried Brenda. He pays for Adam's therapy and tries to maintain a supportive environment for his sons, though he experiences frequent friction regarding his ex-wife's lifestyle and its impact on Adam.

Brenda is Adam's stepmother, described as blonde, pristine, and polite. She keeps a clean, orderly home that contrasts sharply with Carmella's house. She cares for Adam's well-being and openly worries about the safety of his mother's living conditions.

Wendell, nicknamed "Sweetie," is Adam's younger half-brother. He experiences frequent unexplained anxiety and fear. He requires Adam's specific coping strategies, like counting prime numbers together, to relax and fall asleep.

Chuck is the therapist who leads the room 13B support group and conducts individual sessions with Adam. He assigns the group members to pick superhero alter egos to help them leave their anxieties at the door. He actively monitors Adam's medication levels and challenges his resistance to therapy homework.

Thor is a member of the room 13B support group who adopts the Norse god superhero persona. He rarely speaks during sessions, which initially intimidates Adam, but he demonstrates unexpected solidarity with his peers outside the meeting room.

Wonder Woman, whose real name is Connie, is a reliable member of the room 13B support group. She struggles with an eating disorder and strict food preferences, and she eagerly participates in the group's activities, including visiting Adam's church.

Wolverine is a cynical and sometimes abrasive member of the support group. He often makes sarcastic comments or mocks others, though he generally follows along with the group's collective activities, like visiting the church.

Snooki is the only group member who chooses a reality TV star instead of a superhero for her alter ego. She is observant and highly vocal during sessions, often chiming in to relate to other members' struggles.

Green Lantern is a group member who suffers from a compulsion to repeatedly check crosswalks for bodies. He actively engages in group discussions and draws comparisons between OCD and addiction recovery programs.

Ben is Adam's best friend from outside the support group. He is Jewish and largely unaware of the full extent of Adam's therapy, but he is highly understanding of Adam's obvious compulsions, such as counting in the car. He provides Adam with a sense of normalcy.

Father Rick is the priest at the Holy Rosary Church. He is welcoming and open-minded, ensuring Adam and his friends feel comfortable in the sanctuary. He pays close attention to Adam's family situation, frequently asking how Carmella is doing.

Maria is the housekeeper at Robyn's home. She keeps a watchful eye on Robyn and engages in friendly gossip with the teenagers when Adam comes over to visit.

Mrs. Polanski is Adam and Carmella's neighbor across the street. She lives in a house with the exact same layout as theirs, but hers is clean and breathable, serving as a clear reminder of what Adam's home used to be before his mother's hoarding began.