Emmett is a 15-year-old Black teenager from Detroit who enters the high-stakes Babel Communications competition. He is motivated by a desperate need to secure financial stability for his family and pay for his mother's medical care. Athletic and observant, he carries a brass key passed down from his formerly enslaved ancestor, which serves as a reminder to maintain his ethics. He struggles to balance his natural compassion with the ruthless rules of the space competition.

Kaya is a highly intelligent and strategic Japanese teenager competing for a spot on the Eden mission. She immediately proposes an alliance with Emmett, prioritizing teamwork and shared safety over individual isolation. She possesses the unique ability to read people's auras, making her highly empathetic and perceptive of Babel's hidden motives.

Morning is the highly disciplined captain of Genesis 12, a second group of teenagers competing for the Eden mission. She is an exceptional strategist who relies on communication and unity rather than individual ambition. She actively investigates Babel's hidden motives while navigating her feelings for a rival captain.

Marcus Defoe is a powerful, bald Black executive for Babel Communications with a noticeably withered hand. He enforces Babel's ruthless, cutthroat ideology, constantly pushing the teenagers to prioritize personal success over empathy. He actively manipulates the competition to mold the teens into hardened operatives.

Bilal is a good-natured Palestinian teenager who consistently demonstrates hospitality and kindness. In an environment designed to pit teens against one another, he creates a sense of community by hosting card games and encouraging everyone to share their life stories.

Emmett's parents are working-class residents of Detroit who have spent their lives caught in a cycle of poverty. His mother suffers from severe kidney disease, and his father works grueling hours in a factory. They serve as Emmett's moral compass, regularly reminding him to retain his humanity and core values.

Vandemeer is a Dutch doctor assigned to provide medical and psychological care to Emmett and Kaya. He operates under his own set of competitive pressures, as Babel financially rewards medical attendants whose assigned teenagers perform well in the trials.

Roathy is a teenager from China who experienced homelessness before joining the Babel mission. He is extremely competitive and easily provoked, quickly establishing a hostile dynamic with those who stand in his way. He prioritizes his relationship with Isadora above the rest of the group.

Isadora is a Brazilian teenager who approaches the competition with a guarded and calculating demeanor. She refuses to share her past with the group, focusing entirely on securing a spot on the mission alongside Roathy. She frequently resorts to sabotage to advance their collective ranking.

Longwei is a highly capable Chinese teenager who immediately establishes himself as the frontrunner in the Genesis 11 trials. He is fiercely independent, refusing to cooperate in team settings, and prefers to rely entirely on his own exceptional skills to secure his position.

Jasmine is a blonde teenager from Memphis. She joins the competition to save her family from bankruptcy and pay for her mother's medical treatments, sharing the common thread of financial desperation with the other competitors.

Azima is a Kenyan teenager who comes from a rural tribe. She is highly athletic and social, navigating the pressures of the competition while forming close connections with several of the male competitors.

Jaime is a Swiss teenager whom Emmett initially assumes is wealthy. In reality, Jaime's family lost their farm to ecological ruin, leaving them destitute. He frequently spars aggressively against Emmett during training.

Katsu is a large Japanese teenager who enters the competition to support his mother, who suffers from severe depression. He acts as a driver during virtual reality exercises but avoids taking on leadership roles.

Mr. Kapinski is the medical attendant assigned to Roathy and Isadora. Driven by the same financial pressures as the teenagers, he resorts to extreme measures to ensure his assigned competitors succeed.

David Requin is a Babel Communications executive responsible for overseeing the Genesis 12 team. He operates with a gambler's mentality, frequently proposing bets on the outcomes of the high-stakes competitions.

Anton is a competitor on the Genesis 12 team. He follows Morning's leadership and aggressively targets rival team members during group exercises.

Loche is a fierce and dangerous combatant on the Genesis 12 team, known for inflicting severe injuries on his opponents in the fighting ring.

PJ is Emmett's best friend from Detroit. They share a close bond over music and perform together in a group called the Most Excellent Brothers.