Shannon is the middle child of a family of five growing up in Salt Lake City in the late 1970s. She is imaginative and sensitive, often feeling isolated at school and out of place at home. She loves inventing elaborate pretend games and wants nothing more than to find a reliable best friend. Her desire for social acceptance is complicated by her developing anxiety.

Wendy is Shannon's oldest sister, five years her senior. She frequently finds Shannon frustrating and responds with unpredictable anger, causing Shannon to view her as a terrifying, aggressive bear. She is often tasked with babysitting her younger siblings and has a hard time making friends at her own school.

Adrienne is a pretty, blonde girl who bonds with Shannon over elaborate pretend games like Dallas Cowboy cheerleaders. As she grows older, she becomes popular and desires a wide social circle, causing tension with Shannon, who prefers an exclusive best-friend dynamic.

Jen is the undisputed leader of "The Group," a popular ring of girls at school. She dictates the social hierarchy, enforcing strict rules and making her friends line up in order of her preference. Despite her imposing social status, she occasionally drops her guard to share genuine interests with Shannon.

Jenny is Jen's best friend and a fellow middle child in a massive family with eight siblings. She is fiercely protective of her status next to Jen and views Shannon as a direct threat. She tells lies, twists social situations, and actively bullies Shannon to keep her at the bottom of the group's hierarchy.

A busy mother of five children who encourages Shannon to be independent. She provides initial comfort but eventually steps back from the intense conflicts between Shannon and Wendy, expecting the girls to resolve their own disputes.

The patriarch of the family who values obedience and academic success. He praises Shannon for her perfect report card and explicitly compares her good behavior to righteous biblical figures, which fuels jealousy among his other children.

An older, sixth-grade student who shows Shannon a different way to treat classmates. Zara is unreservedly kind to everyone she meets, proving that popularity does not require exclusivity or cruelty.

Zara's best friend and another sixth-grade student. Veronica is quick to validate Shannon's feelings about her old friends, memorably calling the mean girls names to make Shannon laugh.

A foster child who temporarily lives in Shannon's neighborhood. She does not understand Shannon's imaginative games, preferring to play with dolls, and struggles to connect deeply during their brief friendship.

The second-oldest child in Shannon's family. She is closer in age to Wendy and generally excludes Shannon from her daily activities.

One of Shannon's younger siblings. Her games are too simple for Shannon to enjoy, keeping them from bonding tightly.

The youngest child in Shannon's family. His primary role in the household dynamics is being watched by his older sisters when their parents are away.

A younger student at Shannon's school who deals with bullying from her own peers. She and Shannon cross paths while seeking refuge outside the school.

A lower-tier member of The Group who gets placed in the same split-grade classroom as Shannon. She provides Shannon with some familiar company but refuses to engage in Shannon's intense writing projects.

Another peripheral member of The Group. She occasionally spends time with Shannon after school but lacks the creative drive to join in Shannon's pretend games.

A sixth-grade boy and the established class clown. He is notably friendly to Shannon, cheerfully ruffling her hair and letting her play soccer with the older boys.

A girl outside of The Group who genuinely attempts to befriend Shannon. Shannon ultimately rejects her invitation to preserve her own fragile social standing with Jen.

A popular boy in Shannon's grade. He unknowingly hurts Shannon's feelings when The Group calls him on the phone to rate the girls' appearances and he dismisses Shannon entirely.