Miss Ona Vitkus is a 104-year-old Lithuanian immigrant who lives alone in a house surrounded by bird feeders. Initially guarded and somewhat bitter, she agrees to be interviewed for a school project, which slowly unlocks her suppressed memories and language. She is fiercely independent, enjoys performing sleight-of-hand magic tricks, and harbors secrets from her past.

Quinn is a struggling musician who steps in to fulfill his son's weekend obligations at Ona's house. Burdened by guilt over his parenting mistakes and past absences, he plays his childhood guitar as a personal comfort. He hopes to achieve success with a Christian rock band while managing his strained relationship with his ex-wife.

Belle is Quinn's ex-wife, a mother consumed by deep sorrow and worry over her family's genetic history. She struggles to maintain her daily routines, letting her house and personal care deteriorate while attempting to find meaning. She eventually discovers a renewed sense of purpose through an unexpected connection with Ona.

The Boy is a deeply empathetic and detail-oriented youth who loves making lists and tracking Guinness World Records. He exhibits unusual mannerisms, such as counting objects and maintaining a restrained physical demeanor, which isolates him socially. His curiosity about Ona's past initiates a profound oral history project.

Louise is a progressive educator and feminist who teaches literature at an all-boys school during the mid-20th century. She challenges patriarchal norms by introducing female authors into the curriculum and confronting her superiors. She forms an intense, intimate bond with Ona that shapes the rest of Ona's life.

Ted is Belle's current romantic partner and a former Boy Scout leader. He has two living sons and tries to provide stability for Belle, though his presence creates natural tension with Quinn.

Amy is Belle's sister who deals with her own intense feelings of guilt regarding her nephew. She contemplates legal action against a doctor who prescribed medications to the boy, bonding briefly with Quinn over their shared regrets.

Howard is Ona's older husband who inherited a music store from his father. A military veteran who carries unaddressed psychological burdens, he is often sad and uninspired, though he writes original music that hints at deeper emotions.

Frankie is Ona's favorite son, a rebellious young man whose military service leaves a lasting mark on her memory.

Laurentas is a successful heart surgeon connected to a secret from Ona's past. He grows up separated from his origins and lives a largely independent life.

Maud-Lucy is an English tutor who lives in the apartment building constructed by Ona's immigrant parents. She plays a significant role in Ona's early education and later makes a life-altering decision regarding a child.

Viktor is a young man Ona meets at the Midway when she is fourteen years old. He teaches her how to perform card tricks and shares a brief connection with her.

Noah is a young scout brought in to assist Ona with chores. He lacks a strong work ethic and openly complains about having to perform community service for the elderly woman.

Sylvie manages the band that Quinn hopes to join permanently. She holds the power to offer him professional opportunities and evaluate his fit with the group.