Luke is a 12-year-old boy born illegally under the government's Population Law, which restricts families to a maximum of two children. Confined to his family's rural farmhouse and increasingly restricted to his attic bedroom after the surrounding woods are cleared, he spends his days reading and observing the outside world through small air vents. He possesses a cautious nature shaped by a lifetime of hiding, though his severe isolation fuels a deep curiosity about the new Baron housing development built next to his family's property.

Jen is a fellow shadow child living in the wealthy Baron housing development next door to Luke's family farm. Unlike Luke, she comes from a family of privilege with government connections, allowing her access to illegal junk food, the internet, and forged travel passes. She holds strong convictions against the Population Law and actively organizes other hidden children online to protest for their rights.

Jen's stepfather is a wealthy government official who provides his family with a comfortable, privileged lifestyle. He uses his status as a Baron to secure forbidden luxuries and technological access for his hidden stepdaughter. Though he operates within the strict government system, his high position allows him to bend the rules to keep his family comfortable.

Luke's mother is a deeply caring and anxious woman who has spent twelve years keeping her youngest son's existence a secret. She works tirelessly on the family farm and later takes a factory job to help pay the rising property taxes. Her constant fear of government enforcement drives her to establish strict visibility rules for Luke, though she feels heavy guilt over his daily confinement.

Luke's father is a hardworking farmer struggling to support his family under oppressive government regulations. He is gruff and pragmatic, prioritizing the family's survival over Luke's emotional comfort. The loss of his farm's woods and the forced sale of his hogs cause him intense financial stress, leaving him little energy for anything beyond basic preservation.

Matthew is Luke's eldest brother, an active teenager who works long hours on the farm alongside his father. He enjoys the freedoms of a legal citizen, attending school and dating, which creates an unspoken distance between him and his hidden younger brother.

Mark is Luke's fourteen-year-old brother. He frequently teases Luke and occasionally plays pranks pretending to be an authority figure, though he keeps his younger brother's secret faithfully. As he grows older and becomes involved in activities like basketball, he spends less time interacting with Luke indoors.

General Sherwood is the authoritarian leader of the country who seized power following severe famines and droughts. He implemented the strict Population Law limiting families to two children and maintains absolute control over the populace through widespread propaganda and police enforcement.