Homer is a twelve-year-old boy who recently escaped from the Southerland plantation. He carries immense guilt for leaving his mother behind during their flight, as well as a strong sense of responsibility for his seven-year-old sister, Ada. Resourceful and fiercely protective, Homer must quickly learn to survive the dangers of the swamp while adjusting to a life outside the plantation.

Ada is Homer's seven-year-old sister who accompanies him on the terrifying journey into the swamp. Because of her young age and the cruelty she faced at the plantation, she possesses an active imagination, believing in monsters as well as the possibility of flying. Her innocence contrasts with the brutal realities of their escape.

Rose is the mother of Homer and Ada and works as a cook at the Southerland plantation. She raised the plantation owner's rejected daughter, Nora, alongside her own children. Rose sacrifices her own chance at immediate escape to try and help another child, resulting in severe punishment and separation from her son and daughter.

Anna is an enslaved twelve-year-old girl at Southerland who desperately hopes to reunite with the mother she was separated from as a baby. She carries an arrow-shaped scar pointing North, which fuels her determination to run away. Because her optimism makes enslavers uncomfortable, she has been sold multiple times.

Suleman is a skilled, formerly enslaved man who lives independently in the swamp rather than settling in one specific community. Missing three fingers from previous escape attempts, he moves stealthily through the trees and acts as a protector for those seeking freedom. He guides runaways and procures supplies by raiding plantations.

Sanzi is a twelve-year-old girl who was born in the secret swamp community of Freewater. Because she has never experienced enslavement, she struggles to understand the true dangers of the outside world. She idolizes Suleman and constantly seeks adventure, sometimes letting her desire to be a hero overshadow the rules designed to keep her community safe.

Billy is a fourteen-year-old boy living in Freewater who escaped enslavement with his father when he was eight. He stutters as a result of trauma from his time on the plantation. Unlike Sanzi, Billy remembers the horrors of the outside world and prefers the safety of Freewater, though he tries to be brave for his friends.

Nora is the youngest daughter of the Crumb family at Southerland. Born with a large octopus-shaped birthmark on her face, she was rejected by her mother and raised primarily by Rose. Nora chooses not to speak aloud but is highly observant and literate. Witnessing the violence of the plantation forces her to reevaluate her family's morality.

Stokes is the brutal overseer at the Southerland plantation. He takes sadistic pleasure in his job, particularly in hunting down those who attempt to escape. He relies on his dogs and his brothers-in-law to track runaways, viewing the violent retrieval of enslaved people as a point of personal pride.

Mr. Crumb is the wealthy and ruthless owner of the Southerland plantation. He delegates the daily violence of the plantation to his overseer but is fundamentally responsible for the systemic abuse and commodification of the people he enslaves. He focuses heavily on his business arrangements and family status.

Mrs. Crumb is the mistress of Southerland plantation. She directs her anger and frustration regarding her husband's infidelity toward the enslaved people on the property, particularly targeting Ada and Rose with physical abuse. She is deeply concerned with appearances, social status, and maintaining absolute control.

Turner, formerly known as Two Shoes on the plantation, is a man who recently joined Freewater. At Southerland, he wore hand-me-down shoes from Mr. Crumb and directly served the plantation owner. His presence in Freewater makes Homer suspicious, as Turner's loyalties and motives for escaping remain ambiguous.

Ibra is a resident of Freewater and Billy's father. Before escaping, he worked closely with the overseer at his plantation and was forced to brand other enslaved people, an act that deeply traumatized his family. In Freewater, he applies his mathematical and logistical skills to help the community thrive.

Ferdinand is a young boy in Freewater who previously worked in a traveling chain gang digging ditches. He arrived in the swamp with only a stolen knife, which he guards fiercely as a symbol of his survival and new identity. He often clashes with Sanzi due to their opposing views on adventure and caution.

Old Joe is an elderly enslaved man at Southerland who has spent his entire life in bondage, having been gifted to Mr. Crumb at his wedding. Despite viewing escape as impossible for himself due to his age, he quietly resists by stealing small supplies, making toys for children, and sharing vital information.

Mrs. Light is Sanzi and Juna's mother and one of the original six founders of Freewater. Having lost a baby during her own traumatic escape, she is fiercely protective of her community's safety and strictly enforces the rules designed to keep them hidden from the outside world.

Juna is Sanzi's older sister and holds the distinction of being the first child born in Freewater. She is responsible and grounded, taking her role in community ceremonies seriously and assisting newcomers like Homer and Ada in adjusting to their new environment.

Viola is the eldest daughter of the Crumb family. She is entirely absorbed in the social event of her upcoming wedding to another plantation owner's son. She shows no concern for the well-being of the enslaved people working themselves to exhaustion to prepare for her celebration.

Daria is a resident and patroller of Freewater. She assists in defending the borders of their secret community using traps and camouflage. She is preparing to marry Ibra, bringing a rare moment of celebration to the hidden village.

David is a patroller for Freewater and one of the original six founders of the hidden community. He works to protect the borders of their sanctuary from loggers and trackers.

Rick is an incompetent tracker hired by his brother-in-law, Stokes, to help hunt down escaped enslaved people. He relies heavily on Stokes's direction and deeply fears the swamp.

Ron is Stokes's brother-in-law and serves as a tracker for the Southerland plantation. Like Rick, he is highly ineffective at his job and easily frightened by the natural predators of the swamp.