Tally is a 16-year-old Special and a member of the Cutters, an elite enforcement unit created by Dr. Cable. She possesses enhanced senses, indestructible bones, sharpened teeth, and swirling facial tattoos. Though she originally appreciates her superior abilities and icy demeanor, her exposure to the wild and her past connections cause her to question her programming and the strict rules of her city.

Shay is the longest-serving Special and the de facto leader of the Cutters. She firmly believes in the superiority of the Specials and the necessity of keeping the city's population docile. She is fiercely loyal to her unit and frequently clashes with Tally over their priorities, demanding strict adherence to the city's regulations.

David is a Smoky who grew up in the wild, entirely avoiding the cosmetic and mental alterations imposed by the city. He distributes the cure to the brain lesions and actively works to dismantle the city's authoritarian structures. He remembers Tally from before her physical transformations and encourages her to trust her own mind.

Zane is the leader of a mischievous group of Pretties called the Crims. He suffers from physical tremors and weakness after taking an early, damaging version of the cure that ate away at his brain lesions. He wears a tracking collar imposed by the authorities but actively encourages others to break free from their brainwashing.

Dr. Cable is a government scientist and a surgically enhanced Special who leads the Special Circumstances unit. She engineers the physical and psychological alterations of her enforcers to maintain absolute control over the city's population. She views the spreading cure as an immediate threat to her highly stratified society.

Fausto is a physically enhanced Special and a member of Tally and Shay's Cutter unit. He actively participates in the enforcement of the city's laws until he is kidnapped by the Smokies during an ambush in the wild.

Andrew is a villager who formerly lived in an electronically contained pre-Rusty settlement. After Tally previously opened his eyes to the technological boundaries trapping his people, he now roams the wild independently. He allies himself with the Smokies and utilizes his survival skills to aid their resistance.

Peris is a former Pretty and member of the Crims who shared a close bond with Tally before her transformation into a Special. He represents Tally's past life in the city and eventually chooses to leave the urban environment to learn survival skills out in the wild.

David's mother is a rogue scientist who developed the nano pills designed to cure the brain lesions inflicted on the city's population. She studies the effects of the Special operations and actively supports the growing revolution against the city's authorities.