Georgie is a fourth-grade boy with dwarfism who measures exactly 42 inches tall. He uses specific accommodations like a stool to write on the board and a modified desk, but he moves through his environment with determination. He runs a dog-walking business with his best friend Andy, though he strictly handles only the smaller dogs. News of his parents expecting another child triggers deep insecurities about his place in the family and his physical limitations.

Jeanette is a fourth-grade girl who has targeted Georgie since kindergarten. She frequently calls him names and draws unflattering pictures of him during class. Behind her abrasive classroom behavior, she lives in a household with older brothers who speak to her with the same harshness she directs at others.

Andy is a fourth-grade boy of Italian descent and Georgie's closest companion. He enjoys video games and soccer, and he eagerly looks for ways to expand the dog-walking business he shares with Georgie. His home life undergoes significant changes when his grandmother moves in, forcing him to share a bedroom and give up his privacy.

Georgie's parents are professional musicians who play in a symphony orchestra and teach private music lessons. They surround their home with classical music and had early hopes that their child would join their musical traditions. They are highly excited about their new pregnancy, eagerly reading baby books and preparing the house for the new arrival.

Russ is the new kid at school who quickly forms a connection with Andy over shared interests like sports. He attends Andy's church and presents himself as a friendly student with good ideas for advertising. His quick integration into Andy's life causes friction in Andy's existing social circle.

Nonna Rosa is Andy's 65-year-old grandmother who recently moved from Italy to live with his family. She speaks primarily Italian and expects her family to communicate with her in her native language. She maintains strict rules about neatness in the bedroom she shares with Andy.

Allison is a seventh-grade girl whom Georgie considers the prettiest student in her grade. She takes piano lessons from Georgie's mother, though her musical skills are unremarkable. She works on the stage crew for the school play and socializes with the older students.

The unborn child of Georgie's parents, due in May. The pregnancy becomes a central focus of the household, with the parents eagerly tracking the child's physical development. Georgie privately assigns the baby the nickname "Baby Godzilla," imagining a future where the younger sibling rapidly outgrows and overshadows him.

Jeanette's two older brothers live with her and their father. They treat their sister poorly, frequently hurling harsh insults and mocking her attempts to make friends.

Andy's mother manages the household that recently took in her Italian-speaking mother, Nonna Rosa. She often drives the boys around town and tries to mediate the space issues at home.