Rafe is an artistic, highly untrusting sixth-grader entering Hills Village Middle School. Feeling like an outcast and stifled by the school's strict 26-page rulebook, he initiates "Operation R.A.F.E." to systematically break every rule in the code of conduct. He struggles with low self-esteem and frequently channels his anxieties and frustrations into elaborate, imaginative drawings of school staff as monsters.

Leo is Rafe's closest confidant and the primary instigator behind many of the boy's mischievous plans. Often quiet but intensely loyal, he serves as Rafe's sounding board and encourages him to stand out rather than blend into the background. He organizes Rafe's rule-breaking progress with a complex point system modeled after video games.

Jules is Rafe and Georgia's hardworking, devoted single mother. She works double shifts at Swifty's Diner to financially support her family and tries to maintain a peaceful home environment. Her recent engagement to Carl adds stress to her relationship with her children, though she tirelessly seeks the best educational and emotional outcomes for them.

Miller is the chief bully at Hills Village Middle School. Imposing and aggressively territorial, he targets Rafe from the very first day of the academic year. He views Rafe's attempts at being a school rebel as a direct threat to his own tough reputation, constantly finding new ways to intimidate and extort him.

Carl, whom Rafe secretly nicknames "Bear," is Jules's live-in fiancé. Unemployed and perpetually parked on the living room couch with his dog, Ditka, he contributes little to the household. He strictly controls the family's television and consistently demands harsher discipline for Rafe.

Mrs. Donatello is an English teacher at Hills Village Middle School whom Rafe views as a harsh disciplinarian. Despite Rafe's initial resistance and attempts to push her away, she recognizes his artistic talent early on. She attempts to uncover the root of his misbehavior rather than simply issuing blind punishments.

Jeanne is a popular, highly intelligent sixth-grader at Hills Village Middle School. Unlike many of her peers, she notices Rafe and shows genuine curiosity about his well-being. She is heavily involved in school activities and charity fundraisers, representing the ideal successful student that Rafe feels he can never become.

Georgia is Rafe's nine-and-a-half-year-old sister who is currently in the fourth grade. She is nosy, highly vocal, and frequently gets on Rafe's nerves by prying into his personal business. Despite their constant sibling bickering, they share a mutual dislike for their mother's fiancé.

Mrs. Stricker is the vice principal at Hills Village Middle School and the ultimate enforcer of discipline. She is a rigid, no-nonsense administrator who leaves threatening voicemails for parents and consistently catches Rafe during his various rule-breaking stunts.

Mr. Dwight is the principal of Hills Village Middle School. Rafe views him as the ultimate warden of the school, going so far as to imagine him as a monstrous lizard king. He ultimately decides the severe punishments for the school's worst offenders.

Ditka is Carl's hulking, obnoxious pet dog. Like his owner, Ditka takes up significant space in the Khatchadorian household and adds to Rafe's general annoyance with his current living situation.

Mr. Rourke is a teacher at Hills Village Middle School. He contributes to Rafe's negative first impression of the school by loudly yelling at him to sit down when Miller prevents Rafe from taking a seat.

Swifty is the owner and manager of Swifty's Diner, the local restaurant where Jules works double shifts to support her family. He generously allows Jules to display her abstract paintings on the diner's walls for customers to see.

Senõr Wasserman is Rafe's Spanish teacher. In Rafe's highly active imagination, he is visually translated as a cruel bullfighter punishing students with sharp spears, adding to Rafe's fantastical view of the school as a torturous environment.

Mr. Lattimore is the gym teacher at Hills Village Middle School. Rafe pictures him as a vicious military drill instructor running a brutal boot camp for the exhausted students in his physical education classes.