Rosie is a pragmatic, analytical physician and mother of five. Deeply affected by the childhood death of her younger sister, she approaches family challenges with a desire to troubleshoot and protect. Her logical left-brain thinking occasionally clashes with the unpredictable nature of parenting, prompting her to search for concrete solutions to emotional problems.

Penn is an idealistic novelist and stay-at-home father to five children. He relies on storytelling to convey life lessons and offer hope to his family. He prioritizes his children's happiness and authentic self-expression above societal expectations, often operating as the emotional anchor for the household.

Poppy is the youngest child of the Walsh-Adams family, an intelligent and tender-hearted girl who was assigned male at birth and initially named Claude. She expresses her female gender identity early, drawing both family support and external social friction. She is highly observant and searches for ways to confidently exist in a world bound by rigid expectations.

Aggie is a loud, boisterous, and self-proclaimed tomboy who lives next door to the Walsh-Adams family in Seattle. She happily rejects traditional feminine behavior, preferring rough play and independence. She forms an intense, loyal bond with Poppy, designating them as rival princesses who share private confidences.

Roo is the eldest Walsh-Adams sibling. As he enters adolescence, he becomes increasingly moody and critical of his parents' decisions, particularly their choice to obscure parts of their family history in their new community. He often expresses his distress through anger and contrarian academic projects.

Mr. Tongo is an endearing and unorthodox child psychologist. He serves as a radical truth-teller for the Walsh-Adams family, offering pragmatic, slightly humorous advice about navigating child development. He pushes the parents to examine their own assumptions about behavior and society.

Carmelo is Rosie's mother, an independent older woman living in Phoenix. She is fiercely supportive of her grandchildren and acts as a confident, unbothered advocate for their self-expression. She frequently questions Rosie's logical rigidity, encouraging a more flexible approach to family life.

Ben is the studious and thoughtful second-eldest son of the Walsh-Adams family. He tends to process his sibling's transition with logic, openly discussing the social challenges and statistical probabilities of life. He is eager for romantic connection and sometimes struggles to balance family loyalty with his teenage desires.

K is a resourceful and multi-talented clinic worker in Thailand who serves as a mechanic, ambulance driver, and midwife. She is a transgender woman who has built a family by adopting orphaned children. She introduces new philosophies about living openly and accepting life's difficulties.

Marginny is the mother of the Granderson family. She is socially cautious and desires a smooth, uncomplicated integration for her new neighbors, prompting her to suggest keeping parts of their past hidden to avoid confusing the neighborhood children.

Frank is the patriarch of the Granderson family in Seattle. He displays a mixture of curiosity and traditional conventionality, asking direct, sometimes intrusive questions about his neighbors' parenting choices and medical plans.

Cayenne is Aggie's older sister. She projects a stereotypical teenage nonchalance that contrasts with the highly sentimental, earnest affection she receives from her romantic pursuer.

Rigel is one of the Walsh-Adams twin boys. He contributes to the chaotic, energetic environment of the family's home and relies heavily on the family's unity for his sense of security.

Orion is the other Walsh-Adams twin. Like his brothers, he feels the weight of the secrets his family carries, leading to moments of accidental honesty that create social friction.

Nick Sr. is the prejudiced father of one of the Walsh-Adams family's early playmates in Madison. He exhibits volatile, violent behavior and represents the direct hostility that the family fears from the outside world.

Becky is a kindergarten teacher in Madison. She uses school policies and the concept of the "Golden Rule" to mask her discomfort with children who do not adhere to traditional presentation norms.

Mrs. Birkus is a history teacher in Seattle who flags alarming and controversial class projects submitted by her students, serving as a catalyst for family interventions.

Derek is a student in Seattle who makes prejudiced comments, sparking a fistfight that brings deeper social tensions to the surface for his peers.

Jane Doe is a young transgender woman who is treated by Rosie for severe injuries resulting from a hate crime at a college party. Her tragic case deeply impacts the medical staff and forces them to confront the severe dangers of prejudice.

Cindy is a mother in Madison who turns a blind eye to her husband's aggressive and bigoted behavior, opting for passive apologies rather than direct intervention.

Jake is a middle school student in Seattle who participates in spreading rumors and bullying, though he later shows a capacity for regret and attempts to make amends.