Jodahs is a 29-year-old human-Oankali hybrid, known as a construct. Initially expecting to become a male, Jodahs discovers it is transforming into an ooloi, the Oankali's third sex. This unexpected development causes concern because an ooloi construct has never existed and possesses unpredictable genetic abilities. Jodahs struggles to control its physical form and feels a deep attachment to Earth, fearing exile to the Oankali homeship.

Jesusa is a human resister belonging to a hidden mountain village where humans have remained fertile for a century. She suffers from a genetic condition that causes painful tumors. Raised to fear the Oankali as devils, she views integration as a betrayal of her people. She is fiercely loyal to her brother and feels a strong duty to protect humanity's independence.

Nikanj is an Oankali ooloi and one of Jodahs's five parents. As a biological archive of diversity, Nikanj uses its sensory arms to investigate and alter genetic material. It possesses wisdom and patience, reassuring Jodahs that its unprecedented transformation into an ooloi construct is not a flaw. Nikanj attempts to mediate between the strict Oankali laws and the needs of its family on Earth.

Tomás is Jesusa's brother and a fertile human from an isolated mountain village. When Jodahs finds him, he is nearly deaf and blind due to his genetic condition and in deep physical pain. He despises the oppressive rules and forced breeding of his home village, preferring to risk death in the forest rather than return.

Lilith is Jodahs's human mother and the original human survivor awakened by the Oankali a century prior. She has spent decades living with her human and Oankali partners, producing many construct children. Though considered a traitor by human resisters, she continues to cultivate gardens for their use and attempts to bridge the gap between the two species through her lived experience.

Aaor is Jodahs's younger paired sibling, born to an Oankali mother shortly after Jodahs. Initially expected to develop into a female, Aaor instead begins transforming into an ooloi like Jodahs. This complication threatens the family with exile, as the Oankali consider multiple ooloi constructs highly dangerous. Aaor struggles significantly to maintain a stable physical form.

Tino is Jodahs's human father and one of Lilith's partners. He has lived with the Oankali for decades, producing multiple construct children. He worries deeply about his family's safety and the strict Oankali laws that threaten to exile his children.

Ahajas is Jodahs's Oankali mother. As part of the five-parent family, she contributes to the familial support system and provides an Oankali perspective on life, death, and the biological imperative to seed new environments.

Dichaan is Jodahs's Oankali father. He forms part of the core family unit that chooses to go into exile in the forest rather than surrender Jodahs to the homeship.

Akin is an older construct sibling in Jodahs's family. Though primarily active before Jodahs's metamorphosis, his legacy of securing the Mars colony provides the critical third option for human survival that shapes the current political reality on Earth.

Marina is a human woman who was abducted and assaulted by resisters while trying to join the Mars colony. Jodahs heals her physical wounds, and she demonstrates a rare human open-mindedness by accepting the Oankali without prejudice before departing for Mars.

João is a human resister from Brazil who is injured and rescued by the family. Jodahs heals his leg, temporarily changing its appearance to please him. Despite forming a chemical attachment to Jodahs, João maintains his resentment of the Oankali and insists on his independence.

Francisco is a century-old human resister and an elder from the isolated mountain village. For decades, he taught his people that the Oankali were evil. However, upon experiencing Jodahs's healing abilities firsthand, his rigid beliefs are challenged, and he slowly reevaluates his lifelong hostility.

Tehkorahs is an ooloi neighbor in the Oankali village of Lo. It expresses both hope and fear regarding Jodahs's unprecedented development, questioning whether Jodahs's existence will pave the way for future ooloi constructs or lead to disaster.

Santos is a marginalized human from the mountain village with baldness and scaly skin. Because he lacks a sense of smell, he is less susceptible to Oankali pheromones, making him more abrasive and suspicious than others, even after Jodahs heals him.

Javier is a human villager who is disillusioned with the elders' oppressive rules about forced reproduction. He and his partner Paz are willing to leave the village to avoid passing down painful genetic conditions to their children.

Paz is a human woman from the mountain village who refuses to stay and give birth to children doomed to die from genetic conditions. She is fascinated rather than frightened when she finally meets the Oankali.

Inez is Francisco's human partner. She shares his century-long history as a resister, though their plans shift as the Oankali arrive to offer them new choices regarding their future on Earth or Mars.