Lynn is a college student who inherited genes causing Duryea-Gode Disease (DGD) from both parents. Because of this condition, she must adhere to a strict diet and wear a visible medical emblem at all times. She acts as the housemother for a group of fellow DGD carriers, frequently reminding them to complete their chores. She is highly studious and capable of intense focus, though she views her academic pursuits as merely a way to mark time before her symptoms worsen.

Alan is a pre-med student who carries two copies of the DGD gene. He maintains an absolutist view of the disease, going so far as to voluntarily undergo sterilization to prevent passing the condition to a new generation. He is hardworking and ambitious, though he believes these pursuits only distract him from his eventual deterioration. He actively seeks information about his institutionalized mother.

Beatrice is a woman with two copies of the DGD gene who manages Dilg, a well-regarded retreat for symptomatic carriers. She possesses an unusual ability to manage the violent tendencies of the residents under her care. She acts as a guide to Lynn and demonstrates how carriers can live safely while deeply absorbed in creative or scientific interests.

Naomi is Alan's mother and an early sufferer of DGD. She began experiencing severe symptoms when Alan was three years old. She lives as an institutionalized patient at the Dilg facility. She bears severe physical scars and blindness from previous institutional experiences but produces intricate works of visual art while entranced in her daily routine.

Lynn's mother is a DGD carrier who passes the condition on to her daughter. She holds strong religious convictions that make her morally opposed to abortion, hoping modern science will develop effective treatments. She aims to teach Lynn the severity of the illness by exposing her directly to its consequences.

Lynn's father is a DGD carrier who passes the condition on to his daughter. Alongside his wife, he forces Lynn to visit a ward to enforce the rigid dietary rules carriers must follow. He reacts desperately to save his daughter's life during a severe personal crisis.

Alan's grandparents step in to raise him after his mother, Naomi, begins to experience severe symptoms and enters an institution. They provide him with care throughout his childhood, acting out of a sense of obligation and familial guilt.