A 39-year-old assistant professor of genetics in Melbourne who operates on a highly regimented schedule. Living with undiagnosed Asperger's Syndrome, Don struggles to interpret social cues but possesses high intelligence and intense focus. Driven by a logical desire for companionship, he launches the Wife Project, a strict 16-page questionnaire designed to filter out incompatible women.

A 30-year-old graduate student in psychology who earns extra income as a bartender. Rosie is spontaneous, independent, and notoriously late, making her entirely unsuited to Don's strict partnership criteria. She is heavily invested in the Father Project, a covert mission to identify her biological father following her mother's early death.

The 56-year-old head of the psychology department and Don's closest male friend. Gene uses his academic research into human sexuality as a convenient cover for his constant philandering. He frequently acts as Don's coach in social situations, though his guidance serves his own cynical worldview.

A clinical psychologist and Gene's highly patient wife. She serves as a vital sounding board for Don, offering practical and empathetic advice that contrasts sharply with her husband's perspective. She manages her own complicated marriage while actively supporting Don's personal growth.

A physical trainer who raised Rosie until she was twelve. He struggled with personal demons following the death of his partner, Bernadette, leading to a strained and distant relationship with Rosie in her adulthood.

Don's supervisor at the university. She is highly concerned with the institution's public image and smooth operation. Her administrative priorities frequently clash with Don's rigid adherence to academic rules.

Don's elderly neighbor who previously enjoyed a long, happy marriage. She serves as an early inspiration for Don's quest to find a wife. She leaves him a legacy meant to be spent on something completely irrational.

A graduate student in Don's genetics program who relies on a tutor for his English writing. He faces potential expulsion after Don catches him plagiarizing, a situation that challenges Don's rigid sense of right and wrong.

A striking, accomplished ballroom dancer who perfectly meets all the criteria on Don's exhaustive questionnaire. She accompanies him to the faculty ball for their highly anticipated first date.

A baseball fan who bonds with Don over the statistics of the sport. He represents Don's growing ability to form spontaneous connections outside of his standard academic circles.

A candidate for the Father Project who insists on thorough documentation before providing a DNA sample. His rigorous demands force Don to draft an elaborate research proposal to secure his cooperation.

An academic contact at Columbia University who discusses dissertation research with Rosie. She encourages Rosie's potential transition to medical school.

The Dean of the School of Medicine at Columbia University and an acquaintance of Don's. He represents potential future career opportunities for the protagonist in New York.

A New York-based doctor and one of the final candidates on Rosie's Father Project list. He proves to be surprisingly perceptive during Don and Rosie's covert attempt to secure his DNA.

A New York plastic surgeon targeted by the Father Project. Suspicious and unhygienic, his paranoia leads to a chaotic encounter when Don and Rosie attempt to covertly gather a DNA sample.

A local doctor and family friend of Rosie's mother. He is the first candidate approached for the Father Project, willingly providing a blood sample under the guise of a genographic study.

Rosie's late mother, who died in a car accident when Rosie was ten. A former medical student, her complex romantic past during her university days sets the entire Father Project in motion.

Don's sister, whose tragic death from a medical complication severely impacted his family's dynamic. Her passing remains a deep source of unexpressed grief for him.

A fellow student in Rosie's psychology program who escorts her to the faculty ball. He instantly draws Don's strong, uncharacteristic dislike.

An interesting woman Don meets at a dinner date service. Despite enjoying a pleasant conversation with her, he ruthlessly eliminates her as a potential wife simply because she is a vegetarian.

The eight-year-old daughter of Gene and Claudia Barrow. She is one of the few people with whom Don feels comfortable demonstrating open affection.

The sixteen-year-old son of Gene and Claudia Barrow. He interacts well with Don, showing the protagonist's hidden capacity for connecting with younger people.

Don's kind but overbearing mother. She was devastated by the death of her daughter, Michelle, which heavily strained her ongoing relationship with Don.

Don's father, who owns and operates a local hardware store. He maintains a distant relationship with Don, fully expecting his other son to inherit the family business.

Don's unnamed brother who still lives at home. He is expected to eventually take over their father's hardware store.

The elderly mother of a deceased Father Project candidate. Suffering from memory loss, she unwittingly provides Don with a crucial DNA sample after he drives long hours to find her.

A direct, attractive French woman who propositions Don at a cocktail party. She is swiftly eliminated from the Wife Project pool because she fails his strict questionnaire parameters.