Frida is a 39-year-old Chinese American mother living in Philadelphia. She works from home editing a faculty research journal and shares custody of her daughter, Harriet, following a difficult divorce. Struggling with depression, insomnia, and isolation in a new city, a single lapse in judgment leads to her enrollment in a dystopian government rehabilitation program. She desperately wants to prove her maternal fitness to the state so she can return to her child.

Harriet is Frida and Gust's toddler daughter. Before the novel's main events, she splits her time between her parents' homes. She loves her mother but functions entirely on a toddler's developmental level, craving familiar routines and comfort. The government's sudden intervention leaves her highly confused and upset.

Gust is Frida's 42-year-old white ex-husband. He left his marriage to Frida shortly after Harriet's birth to pursue a relationship with Susanna. Though he initiated the divorce, he still wants Frida involved in Harriet's life and tries to negotiate boundaries in their new co-parenting dynamic.

Susanna is Gust's 28-year-old girlfriend, a part-time Pilates instructor who receives a monthly allowance from her wealthy parents. She becomes heavily involved in co-parenting Harriet, suggesting new-age strategies like gluten-free diets and cloth diapers that often clash with Frida's reality.

Renee is Frida's divorce lawyer and close friend. Recognizing the aggressive and biased nature of the family court system, she advises Frida to act compliant, hide her depression, and appear as non-threatening as possible to survive the ordeal.

Frida's parents are Chinese immigrants and retired economics professors living in Illinois. They financially support Frida but maintain a reserved, traditionally Chinese parenting style that American therapists frequently misinterpret as emotional abandonment.

Will is a 38-year-old cultural anthropology PhD student and Gust's best friend. He serves as Harriet's godfather and is Frida's only real friend in Philadelphia. He has a history of dating sad women and offers Frida emotional support and flirtatious attention during her crisis.

Ms. Torres is the Child Protective Services social worker assigned to Frida's case. She coordinates supervised visits but fails to understand toddler development, forcing unnatural play scenarios that upset Harriet and disadvantage Frida.

Emmanuelle is an advanced AI robot doll programmed to look and act like a toddler of Harriet's exact age and demographics. She contains internal cameras to monitor Frida's emotional responses and evaluates her maternal fitness for the state.

Tucker is a divorced scientist attending the nearby rehabilitative school for bad fathers. He was institutionalized after his son broke a leg while Tucker was texting. He is optimistic, validates Frida's mothering, and pursues a romance with her despite the strict rules against fraternization.

Helen is an older mother sent to the program for coddling her 17-year-old son by cutting his food and tying his shoes. She dislikes the program's psychological pressure and exercises her option to quit on the first day.

Lucretia is a friendly Black mother sent to the institution because her daughter broke an arm falling off a slide. She questions the instructors' credentials and struggles when her doll malfunctions in the snow.

Linda is a Latina mother whose six children are dispersed across the foster care system. She is a highly capable student in the program, quickly mastering the artificial drills, which breeds resentment among her struggling peers.

Meryl is a white teenage mother enrolled in the program after struggling with drug use and hitting her daughter. She feels targeted by the instructors due to her youth and leans on older mothers for emotional support.

Beth is a young white mother who previously spent time in a psychiatric ward. She bonds closely with Frida and Meryl as they survive the confusing and painful lessons inflicted on their AI dolls.

Roxane is a young Black woman sent to the school because she allowed her tween niece to babysit her infant son during an unexpected work shift. She grieves missing her baby's developmental milestones while institutionalized.

Ms. Knight is the director of the rehabilitative institution. She firmly believes that poor parenting causes societal decay and strictly enforces the program's rules, expelling mothers for minor infractions and terminating their parental rights.

Ms. Russo is an instructor at the school who teaches the curriculum by forcing the mothers into emotionally abusive scenarios with the dolls. She expects impossible feats of maternal devotion.

Ms. Khoury is an instructor who guides the mothers through the physical maintenance of the AI dolls, including draining their toxic blue coolant—a process that traumatizes the robots.

Jeremy is the three-year-old AI robot doll assigned to Tucker at the school for bad fathers. He interacts with the mothers' dolls during socialization exercises.