Sam is a loud, cocky fifth-grade student who goes by the nickname Snik. As the new kid at Grand Canyon School, he tries to project a cool image and openly dislikes homework, often providing sarcastic answers to assignments. He is deeply proud of his father, who serves in the Air Force, which fuels his pro-military views. Beneath his tough exterior and academic struggles, he possesses a quick wit and a hidden capacity for strategic thinking.

Kelsey is a laid-back fifth grader who uses pink hair dye and a belly-button piercing to express her individuality. She projects an air of apathy toward schoolwork, content to coast by with average grades rather than exert effort. Having lost her father in a tragic accident at a young age, she possesses a grounded perspective on what truly matters, making her highly empathetic toward the struggles of others.

Judy is an anxious, high-achieving student in the gifted and talented program at Grand Canyon School. As a straight-A student with aspirations of attending law school, she takes rules and academic integrity seriously. She is hyper-focused on her future and often feels the weight of high expectations, which makes her easily stressed by anything that threatens her pristine record or moral standards.

Brenton is an eccentric child prodigy and computer genius who finds himself isolated from his fifth-grade peers. He uses his vast intellect to study psychology, physics, and medicine, viewing typical social structures as fascinating experiments rather than things to participate in. He operates outside the traditional middle school hierarchy, genuinely unbothered by his lack of friends until he begins interacting more closely with his tablemates over his secret invention.

Miss Rasmussen is the enthusiastic and caring new fifth-grade teacher at Grand Canyon School. A nature lover fresh out of teacher training, she embraces creative teaching methods and encourages her students to express their individuality. Though sometimes naive about middle school social dynamics, she genuinely wants the best for her diverse class and looks for the good in every student.

Ronnie is a solitary fifth-grade student who keeps a close eye on his classmates. Lacking a friend group of his own, he is highly suspicious of the newfound bond between the members of the D Squad. He is persistent, nosy, and determined to uncover whatever secret is keeping the four disparate students together.

Rebecca Fish is the gruff but observant police chief of Grand Canyon, Arizona. Tasked with reviewing unusual cases, she listens to the testimonies of students, parents, and teachers. Despite her tough exterior, she maintains a fair and perceptive approach to the children in her community.

Richard Milner is a persistent adult who monitors internet trends and seeks out the individuals responsible for them. He frequently messages the students online, attempting to gather information about their viral school activities and creating a sense of unease among the fifth graders.

Mr. Dawkins is Sam's father, an active-duty member of the Air Force. He instills a strong sense of military pride and resilience in his son. He maintains a close connection with Sam through a shared love of chess, offering guidance and support when deployed overseas.

Sam's mother is a supportive parent who manages the challenges of military family life. She is attentive to Sam's struggles with moving and school rules, striking deals with him to encourage him to complete his homework while allowing him some personal expression.

Brenton's mother is deeply proud of her son's intellect but worries about his lack of socialization. She is thrilled and exceptionally welcoming when Brenton brings classmates home for the first time, eager to support his integration into a normal social life.

Mr. Damagatchi is Brenton's father. He works with computers and unwittingly supplies his son with the powerful equipment needed to run complex software programs. He is often busy with his own career but provides a stable environment for his genius son.

Judy's mother is an attentive parent who holds high expectations for her daughter. As part of one of the few African American families in the area, she is highly protective of Judy and mindful of societal dynamics, encouraging her daughter to maintain her strong moral compass.

Judy's father is a strong household presence who values education and ethics. He frequently initiates discussions about complex topics like gun control and morality during family dinners, fostering Judy's analytical skills and ethical awareness.

Kelsey's mother is a working-class single parent who loves her daughter but maintains a highly permissive parenting style. She allows Kelsey to dye her hair and get piercings, and is pleasantly surprised when Kelsey shows sudden academic improvement.

Jessica is Judy's long-time best friend from kindergarten. She belongs to the school's high-achieving social circle and is highly critical of students from other cliques, becoming resentful when Judy begins spending time outside their usual group.

Heather is a member of Kelsey's original, laid-back friend group. She strongly disapproves of Kelsey's sudden association with the school's high achievers and attempts to dictate Kelsey's social choices.

Principal Wilson is the head administrator at Grand Canyon School. He handles disciplinary issues and oversees the teachers and students, representing the ultimate academic authority in the school hierarchy.