Marilyn is Lydia's mother, a woman with ambitions of becoming a doctor who becomes a homemaker instead. She projects her unfulfilled dreams onto Lydia, pushing her daughter to achieve what she could not.

James is Lydia's father, a Chinese American man who struggles with his sense of belonging and acceptance in a mostly White society. He favors Lydia for her appearance and social potential, mirroring his own experiences and desires.

Nath is Lydia's older brother, who shares his father's physical appearance and confronts similar pressures of fitting in. He develops a keen interest in space exploration and works towards his dream of attending Harvard.

Hannah is Lydia's younger sister, often overlooked in the family. Observant and sensitive, she sees things others do not and grows into her own as she gains more attention following Lydia's disappearance.

Jack is Nath's schoolmate, initially perceived as a carefree and rebellious character. He becomes an important confidant to Lydia and shares a complicated, evolving relationship with Nath.

Louisa is James's former graduate student and assistant, a young Chinese American woman who provides James with a sense of comfort and cultural belonging during a challenging time.