David is a fourteen-year-old middle child living in a busy household where he often feels overlooked. He harbors a deep passion for the niche sport of competitive eating and possesses a fast metabolism that allows him to consume massive quantities of food. After an online auction for a piece of competitive eating memorabilia goes horribly wrong, he scrambles to find a way to pay off a massive accidental credit card charge.

Mal is David's ten-year-old brother who has autism and interacts with the world through a highly specific set of sensory rules. He is largely nonverbal, communicating his needs and feelings primarily through the word "okay" and subtle shifts in body language. He relies on strict routines, specific safe foods like potato chips, and a rolled-up industrial carpet to soothe him during periods of intense overstimulation.

Mom manages the complex daily operations of the Miller household, maintaining a hyper-vigilant watch over Mal's needs and routines. She relies heavily on David to act as a secondary caretaker during the summer so she can focus on her own work. She views competitive eating as a wasteful and disgusting habit, putting her directly at odds with David's ambitions.

Dad works long hours to support the family financially, often leaving Mom and David to handle the immediate household crises. He possesses a hyperactive energy and tends to leap from project to project when he is off the clock. He is practical and hands-on, famously bringing home the industrial carpet scrap that became an essential tool for calming Mal.

Bridgette is David's older sister, a high-achieving college student who returns home periodically for meals. She is highly focused on her academic success and projects an image of perfection. Her achievements and attitude often make David feel inferior and overlooked within the family dynamic.

Hayden "HeyMan" Mankowski is one of David's two closest friends. He is exceptionally hairy for a fourteen-year-old and shares David's enthusiastic interest in the eccentric world of competitive eating. He acts as a supportive sounding board and occasional financial backer for David's various eating schemes.

Cyn is a Korean American teenager who completes David's tight-knit trio of best friends. Having known David since the first grade, she serves as the group's intellectual anchor. She provides internet research, sharp observations, and grounded logic that the two boys frequently lack.

Derek is Bridgette's college boyfriend who views himself as worldly and knowledgeable. He is the only person at the Miller family dinner who shows genuine interest in David's speed-eating abilities, later tipping David off to a local slider-eating contest.

Jooky Garafalo is a legendary competitive eater and David's personal idol in the sport. He is famous for losing the Nathan's Famous contest by a mere half-hot dog, an iconic piece of food that becomes the center of David's massive financial mistake.

The Gurge is a notorious figure in the competitive eating community. While he is capable of impressive eating feats, he is equally infamous for facing multiple accusations of cheating and engaging in highly unscrupulous behavior during professional contests.

Egon Belt is an older, professional competitive eater who holds multiple regional records. He encounters David during a pizza-eating practice session and models a steady, methodical approach to the sport, contrasting sharply with David's frantic, painful style.

Papa Pigorino is the local restaurant owner who decides to host a massive pizza-eating contest with a five-thousand-dollar grand prize. His contest provides David with a desperate potential solution to his pressing financial crisis.