“Bloodchild” takes place on an unnamed planet inhabited by an alien species called Tlic, who resemble three-meter long centipedes. Their society is dominated by females as the males have a very brief if sexually charged lifespan. The Tlic reproduce by laying their fertile eggs in other living organisms where the larvae feed off of the host creature’s blood. When the larvae hatch, they release a poison into the host’s body and begin eating out of their egg cases and then continuing to consume the host.

Humans arrived on the Tlic homeworld in a time of crisis: the host animals which the Tlic were accustomed to using evolved a natural defense against Tlic infestation and therefore posed a great threat to the future of Tlic existence. When the Terrans landed, fleeing persecution by other humans on another planet, the Tlic seized the opportunity to use the newcomers as host organisms, treating the humans as animals penned up in cages and fed only on the intoxicating and placating sterile Tlic eggs.

Eventually, the Tlic government did away with this system in favor of a more symbiotic relationship with humans. Instead of breaking up Terran families and treating them as dumb animals, the Tlic allow and encourage the Terrans to maintain a family, household, and livelihood in the Preserve – a specific set of land set aside for human use and protection. Each human family then is “adopted” by a Tlic female who deposits her eggs into one of the family’s children, usually a male so that the females can bear human children. Instead of leaving the humans to be consumed in birth, the larvae are extracted before they set to eating the host’s body.

T’Gatoi is a Tlic government official who is in charge of the Preserve. She is very close to her human family and describes their home as a “place of refuge.” She has been promised Gan, the younger son of the family, as a carrier for her eggs. On the day Gan is to be implanted with the larvae, an N’Tlic, a human who is carrying a Tlic’s eggs, stumbles upon the family’s house just as the larvae he carries are hatching. His Tlic is not present. T’Gatoi is forced to birth the larvae. All Tlic births are violent – the Tlic must cut open the human and remove all the larvae from the abdominal cavity. If the Tlic misses even one larva, that infant Tlic will poison and kill the Terran host. A birth performed by a Tlic other than the one whose eggs are hatching is even worse because the human N’Tlic cannot be fully anesthetized. Gan offers to help T’Gatoi with the birth despite her warnings against it and he finds that he is revolted and disgusted by the process, causing him to rethink his willingness to be N’Tlic for T’Gatoi, especially after he hears Qui tell him of a birth he witnessed where the Tlic allowed the larvae to completely consume the Terran host because the Tlic had nowhere else to put the voracious grubs.

Gan faces a crisis; he has grown up believing this relationship to be “good and necessary,” but now he is fundamentally repulsed by its very nature. He wants to believe there is more to the situation than just the base manipulation of humans to use them as hosts. He threatens to kill himself, then almost passes on the responsibility to his willing sister Xuan Hoa. Ultimately, however, he accepts his role as an N’Tlic voluntarily. While T’Gatoi implants her eggs in his abdomen, he admits to himself that he would not have wanted T’Gatoi to use anyone else because he wanted her for himself.

T’Gatoi is a prominent Tlic politician who is in charge of The Preserve, where humans (called Terrans) live. Her influence and protection allows for the symbiotic relationship between humans and Tlic. She is also the adoptive head of Lien’s family, just as every Terran family has a Tlic female as its head. She and Lien “grew up together,” so to speak, even though human and Tlic development are quite different; however, T’Gatoi went through a phase of accelerated growth, an adolescence of sorts at the same time Lien was growing up as a human child and the two became good friends. Eventually T’Gatoi introduced Lien to her future husband, interestingly enough the same human male who had borne T’Gatoi as a larva.

Lien is the human mother of the family; her husband who carried T’Gatoi has died. Lien, knowing that she would have to give one of her children to a Tlic, chooses to make that promise to T’Gatoi, a Tlic she knows and feels she can trust. As she grows older, she grows away from T’Gatoi and begins to regret her decision; she feels that she is selling her son.

Gan, the younger of two sons, is the one chosen for T’Gatoi. He has been raised in her presence since his birth and spent time with her in the city, outside of the preserve; he seems to serve as an ambassador of sorts for the Preserve and its function in Tlic society.

Qui is the oldest son of the family and he is very resentful of the Tlic because he has observed a man being eaten by the Tlic larva he was carrying after they hatched and had nowhere else to go. He perceives the Terrans as being used like cattle, being lied to and deceived. His goal is only to escape, though that is impossible in a literal sense; instead, he contents himself with the consumption of sterile Tlic eggs, which have an intoxicating effect on humans. Gan later says that the escape Qui is looking for is death.

Xuan Hoa is Gan’s older sister. She also likes T’Gatoi and wanted to be the one chosen as her N’Tlic (egg carrier). However, T’Gatoi decided on Gan, who was yet unborn at the time, because she wanted to be able to be a part of the child’s development every step of the way.

There is a second sister who is not named and does not play a significant part in the story.

Bram Lomas is an N’Tlic who stumble upon Lien’s house just as the larva he is carrying are hatching. His Tlic, named T’Khotgif, is not present and the situation is quite dire.

T’Khotgif is Lomas’s Tlic; she was ill and therefore unable to come to Lomas’s aid immediately.

A Terran doctor also comes to help take care of Lomas.