Letta is a teenager approaching her eighteenth birthday. She works as an apprentice wordsmith in the post-apocalyptic city of Ark. Her job involves collecting, cataloging, and erasing words to fit the authoritarian regime's approved language. Orphaned at a young age, she initially believes strongly in Ark's mission until her exposure to rebel artists forces her to reconsider her loyalties.

Marlo is a young man belonging to the Creators, a group of artists labeled as Desecrators by the authorities. He sustains an injury from the enforcers and ends up under Letta's care. He advocates for individual freedom and refuses to suppress human emotion for the sake of strict societal order.

John Noa is the charismatic founder and dictator of Ark. He predicted the catastrophic floods known as the Melting and built a sanctuary for survivors. He firmly blames language for human greed and disaster, leading him to enforce strict communication laws while secretly developing a chemical to eliminate speech entirely.

Benjamin is the master wordsmith of Ark. He is an academic who warned people about global warming before the Melting occurred. He maintains the city's language archives but grows increasingly uncomfortable with the regime's direction, eventually going missing on a routine trip.

Amelia is the second-most powerful person in Ark and resides with John Noa. She suffers from a severe breathing problem rumored to be caused by chemical exposure. She operates closely with the regime but harbors her own complicated family history.

Finn is a massive, bearded man who serves as a leader among the Creators. He organizes resistance activities against John Noa's regime and coordinates safe passage for outcasts. He fights to preserve art, music, and emotional expression in a world that outlaws them.

Leyla is a musician and member of the Creators who formerly worked alongside John Noa. She refers to herself as a "color-catcher" who uses music to preserve memories, including painful ones. She lives in hiding to perform her art.

Carver is a strict gavver who serves as an enforcer for John Noa. He speaks in broken, rudimentary language as mandated by Ark law. He polices the citizens ruthlessly and suspects Letta of harboring secrets.

Werber is an arrogant young man working at Ark's water station. He is a "third child" who was given to another family due to strict population laws. He desires Letta as a mate and frequently seeks her attention.

Mrs. Truckle is a schoolteacher in Ark. She relies on the wordsmiths to provide the approved vocabulary cards for her students. She privately harbors distaste for the regime's harsh punishment system.

Daniel is the son of Ark's healer and his wife, Rose. He works as an apprentice carpenter until he is arrested by the gavvers for stealing potatoes. His capture leads to severe punishment and banishment.

Rose is the wife of the local healer and the mother of Daniel. She becomes desperate when her son is arrested, turning to prayer at the Goddess statue and begging Letta for assistance.

John Lurt is the official healer in Ark. He provides medical care but becomes hardened and suspicious after the authorities arrest his son, Daniel.

Hugo is an elderly painter and Creator. He refuses to hide his artwork, resulting in a severe beating and imprisonment by the gavvers. From his cell, he directs Letta to a secret communication drop.

Smith Fearfall is a scavenger who lives in the shantytown of Tintown. He collects discarded items and answers directly to John Noa, who forces him to lie about discovering Benjamin Lazlo's remains.

Edgeware is known to the locals as the Black Woman of the Woods. She lives in exile outside Ark, rescuing banished citizens and using herbal remedies to treat their wounds. She carries grief over a son who was brutalized by Noa's early experiments.

Solam Tellon is an older scientist living in the squalor of Tintown. Because scientists were unwelcome in Ark after the Melting, he lives in poverty. He possesses crucial knowledge about the chemical compound Nicene.

Kirch Tellon is a young man living in Tintown. He assists Letta in navigating the dangerous shantytown and serves as a local guide.

Freya is Letta's missing mother. She was a sailor who undertook an exploratory voyage when Letta was only four years old and never returned. Her disappearance heavily shapes Letta's feelings of isolation.