Anthony is a fourteen-year-old eighth-grader living in Brooklyn, New York. Known primarily by his nickname, he is the middle child in a loud Italian American family. He frequently feels overlooked compared to his siblings and often acts as the family peacemaker. Though self-deprecating and quick with a sarcastic joke, he possesses a strong sense of loyalty and a good heart.

Calvin is a thin, wispy-haired boy who is completely nondescript and virtually unnoticeable to his peers and teachers. He suffers from what Anthony dubs the "Schwa Effect," causing him to blend into his surroundings so thoroughly that people forget he is there. He lives alone with his father and carries a deep fear of fully disappearing.

Mr. Crawley is an elderly, wealthy recluse known for his cantankerous attitude. He lives above his massive Brooklyn restaurant with a pack of fourteen Afghan hounds. Currently using a wheelchair due to a broken hip, he exerts considerable social influence over the neighborhood and demands total obedience from those around him.

Lexie is Mr. Crawley's fourteen-year-old granddaughter. She has been totally blind since a fall at the age of three but moves through her surroundings with immense confidence and perceptive intuition. She is a firm advocate for the blind and refuses to let others treat her as helpless.

Anthony's mother is an expressive Italian American homemaker who rules her kitchen with an iron fist. She takes immense pride in her role as the family cook and caregiver. She frequently bickers with her husband, though these arguments mask deeper feelings of being restricted to her domestic role.

Anthony's father is an executive in product development at Pisher Plastic Products. Despite his corporate job, his true passion lies in cooking, an interest that often puts him at odds with his wife's culinary dominance. He can sometimes be oblivious to the emotional nuances of his household.

Howie is one of Anthony's oldest friends. He is literal-minded, favoring math and science over creative pursuits. He struggles to accept changes in his social circle, particularly the addition of Calvin.

Ira is Anthony's other longtime friend. He is an aspiring filmmaker who loves being in control and being the center of attention. He actively dislikes Calvin, preferring to distance himself from the unusual boy.

Frankie is Anthony's older brother. He earns straight A's in school and is treated by their parents as the golden child of the family, leaving Anthony feeling inferior by comparison.

Christina is Anthony's younger sister. She is doted on by their parents, further contributing to Anthony's feelings of being the overlooked middle child.

Mr. Schwa is Calvin's father, a housepainter who suffered a mild traumatic brain injury after falling off a ladder. The injury left him with severe short-term memory problems, requiring Calvin to care for him and post reminder notes around their house.

Calvin's mother disappeared when he was five years old while waiting in a checkout line. Her absence haunts Calvin, leaving him with a deep fear that he too will simply vanish if no one remembers him.

Mr. Werthog is the science teacher at Anthony's school. He suffers from an unfortunate lip tic and serves as one of the adult test subjects for the "Schwa Effect."

Wendell is a thickheaded classmate of Anthony and Calvin. He pays Calvin to complete dangerous or foolish dares, taking advantage of Calvin's unnoticeable nature.

Moxie is Lexie's seeing-eye dog. Lexie named her after the antibiotic amoxicillin because it made her feel better as a child, just as Moxie makes her feel more positive about navigating the world.

Gunther is the wild-eyed Night Butcher at the supermarket where Calvin's mother disappeared. Having worked there for nineteen years, he holds crucial information about the events of that day.

Oscar was the day butcher at Waldbaum's supermarket. He was known for being good at handling emotional customers.