Aza is a sixteen-year-old high school student living in Indianapolis who struggles daily with obsessive-compulsive disorder and severe anxiety, particularly concerning bacterial infections. Following the death of her father, she holds tightly to his memory by driving his old car, Harold, and looking at photos on his cell phone. To cope with her overwhelming fears, she repeatedly presses her thumbnail into a callus on her finger to ground herself, creating a wound she feels compelled to constantly clean and bandage.

Daisy is Aza's extroverted and talkative best friend who works a low-paying job at Chuck E. Cheese to save for college. Coming from a lower-income family, she is acutely aware of socioeconomic differences and views the reward money for a missing billionaire as an opportunity to change her life. She writes highly popular Star Wars fan fiction as a creative outlet and a way to process her frustrations.

Russell, commonly known as Davis, is a wealthy high school student living on a massive, highly secure estate. Despite his family's vast wealth, he suffers from intense loneliness following his mother's death and his father's sudden disappearance to avoid fraud charges. He writes poetry and blog posts about the universe and questions whether people value him for his personality or his money.

Aza's Mother is a math teacher at the same high school Aza attends. As a widow, she carries the grief of losing her husband alongside an intense, hovering fear for her daughter's mental well-being. She struggles to balance her protective instincts with Aza's need for independence and frequently questions Aza about her anxiety levels.

Mychal is an artistic high school student who frequently spends time with Aza and Daisy. He creates unique art installations and feels somewhat out of place among the more pretentious elements of the local art scene. He is mild-mannered but genuine in his interactions with his friends.

Noah is Davis's younger brother, who is deeply affected by their father's sudden disappearance. Too young to clearly remember their late mother, he clings to the hope that his father loves them and will return. His distress manifests in behavioral issues and desperate attempts to find clues about his father's location.

Russell Davis Pickett, Sr. is a local billionaire and the CEO of a major engineering firm who has disappeared to avoid arrest for fraud and bribery related to a city sewer project. He is known for his eccentricities, including planning to leave his entire massive fortune to his pet tuatara rather than his two sons.

Dr. Singh is Aza's psychiatrist, tasked with helping the teenager manage her severe obsessive-compulsive disorder and anxiety. She emphasizes the importance of medication and cognitive exercises, attempting to frame Aza's daily struggles as a form of courage rather than a weakness.

Lyle is the head of security for the sprawling Pickett estate. He enforces the property's strict boundaries and protects the privacy of the Pickett family, though he also facilitates transportation around the massive grounds for Davis and his guests.

Malik is the resident zoologist at the Pickett estate. He is exclusively employed to care for Russell Pickett Sr.'s tuatara, a rare reptile that the billionaire believes holds the key to extended human life.

Rosa is the house manager for the Pickett estate. With the boys' mother deceased and their father missing, Rosa ensures they are fed and the household runs smoothly, functioning as a paid caregiver for the brothers.

Simon Morris is the lawyer representing the Pickett family. He handles the legal and financial logistics for Davis, including arranging appointments at the bank to ensure large cash deposits are handled without causing legal trouble.