Martin is a smart, sarcastic 13-year-old boy who has been expelled from every school he has attended. He relies on his sharp tongue and a habit of insulting authority figures as a defense mechanism, a behavior born from years of verbal hostility at home. Despite his prickly exterior, he is highly observant and quickly notices unusual patterns in his new friends' behaviors.

Torchie is Martin's friendly and welcoming roommate at Edgeview Alternative School. He constantly finds himself at the center of sudden fires, though he intensely insists that the flames are not his fault. He forms the core of Martin's new social group and tries to keep the peace among the boys.

Cheater is a brilliant student who consistently receives failing grades because teachers believe he copies other students' tests. He fears that people dislike him because of his Chinese heritage and worries deeply that his uncanny ability to know other people's answers points to mental illness.

Flinch is a tall, nervous boy with a skinny build known for his habit of ducking right before objects hit him. He is highly athletic, incredibly skilled at arcade games, and loves inventing jokes. His jumpy nature stems from an unusual awareness of what is about to happen around him.

Lucky is a large, good-natured boy who anchors the group of friends at Edgeview. He occasionally argues with invisible entities and frequently acquires lost items, leading to persistent accusations of theft. Despite his size, he is peaceful and deeply loyal to his smaller friends.

Trash is an isolated student initially shunned by others because objects violently fly away from him, leaving his surroundings wrecked. Beneath his destructive exterior, he is a talented artist who draws intricate spaceships and alien planets in his heavily damaged room.

Bloodbath is a cruel, 16-year-old bully who dominates the student body at Edgeview Alternative School. He routinely beats up younger boys, steals their belongings, and delights in causing misery for anyone smaller than him.

Mr. Briggs is an enthusiastic science teacher at Edgeview who genuinely cares about his troubled students. Having been pushed out of regular schools for his unconventional methods, he finds purpose at Edgeview and demonstrates immense patience with Martin's relentless sarcasm.

Principal Davis is the middle-aged, long-suffering administrator of Edgeview Alternative School. He approaches the school's myriad problems with a strict, bureaucratic mindset and openly dislikes Martin's aggravating attitude from their very first interaction.

Ms. Nomad is an earnest, idealistic young English teacher who writes sincere but poorly composed poetry. Her overly enthusiastic teaching style frequently makes her a target for Martin's biting insults, though she genuinely wants to inspire her students' creativity.

Ms. Crenshaw is an unconventional history teacher who uses theatrical roleplay to engage the students at Edgeview. She harbors dreams of being a theater instructor, a professional vulnerability Martin quickly identifies and mocks.

Mr. Langhorn is a rigid and aggressive geography teacher whose classroom management style relies on intimidation. He routinely yells, snaps at students, and demands absolute silence, making him a universally disliked figure among the boys.

Waylon, known almost exclusively as Hindenburg, is an Edgeview student infamous for his severe flatulence. His unfortunate digestive issues inadvertently contribute to the chaotic environment of the school when he runs afoul of the local bullies.

Richard is Martin's father, a quick-tempered man who frequently bullies his family members verbally. He refuses to take any responsibility for Martin's behavioral issues, instead blaming the boy entirely while dominating the household atmosphere with his anger.

Dorothy is Martin's timid mother. Though she loves her son and misses him terribly while he is at Edgeview, she lacks the courage to stand up to her husband's overbearing and angry nature.

Teri is Martin's supportive sister who stays in touch with him via letters while he is away at Edgeview. She bears the brunt of their father's difficult temper while Martin is gone, serving as a vital emotional anchor to his life back home.

Lip is a small, unattractive student with bad teeth who serves as Bloodbath's devoted sidekick. Despite his lack of physical power, he eagerly participates in intimidating the younger boys and acts as an audience for Bloodbath's cruelty.

Mr. Parsons is a balding math teacher at Edgeview who experiments with unconventional teaching methods, including musical lessons. He quickly loses patience with Martin after the boy publicly mocks his comb-over during class introductions.

Dr. Harper is a professional tasked with evaluating Edgeview Alternative School's viability. She harbors private career disappointments and personal desires, which Martin uniquely senses during his formal interview with the inspection panel.

Walden is a large local football player and the son of the town mayor. He harbors a strong prejudice against the alternative school students and attempts to physically drive them out of town using his athletic size to intimidate them.