Character Profiles are for Guidance Only

Catherine is Robert's twenty-five-year-old daughter. A college dropout, she has spent several years at home caring for her mentally ill father. A few years earlier, when his illness went into remission for almost a year, she enrolled as a sophomore at Northwestern University in Evanston, Illinois. She dropped out of that program and returned to look after her father when he again became ill. Their relationship, although sometimes antagonistic on the surface, was sustained by strong mutual affection. Catherine is worried that she may inherit her father's illness, and the signs of mental instability are already there. Although she is a highly intelligent woman, she has no direction in life and often, according to her father, sleeps till noon. Some days she does not even get out of bed. She is obviously suffering from depression, and her attitude about life is bitter. Claire, her sister, wants her to move to New York so she can keep an eye on her and arrange for the best medical treatment, but Catherine resents her interference. Evidence of her unstable mental condition emerges in Claire's report of her aggressive behaviour toward the police officers who came to the house after Catherine reported a burglary in progress (which was her extreme reaction to Hal's attempt to smuggle out one of her father's notebooks). Hal attempts to befriend Catherine. She then takes the lead and seduces him. Wanting to show affection and trust, she allows him to discover the amazing mathematical proof that she has written in one of her father's notebooks. She is upset when Hal does not believe she wrote it and feels that her trust in him has been betrayed. Eventually, Hal is convinced that she wrote the proof, and the mathematical genius that Catherine inherited from her father is finally revealed and acknowledged. It appears that Catherine and Hal may be on their way to a rewarding relationship, both professionally and personally.

Claire is Catherine's efficient, practical, and successful sister. Unlike Catherine, she has inherited none of her father's erratic genius. Instead, she has made a career in New York as a currency analyst. She made enough money to pay off the mortgage on the family home in Chicago, even when she was living in a studio apartment in Brooklyn, New York. Claire lives with her boyfriend, Mitch, who also has a successful career, and they plan to marry in January. Claire and Catherine have never gotten along well, and when Claire returns from New York for their father's funeral, they quarrel. Claire feels responsible for Catherine's welfare and wants her to move to New York, but Catherine resents what she sees as Claire's interference in her life. It transpires that they have quarrelled in the past over how to care for their father. Claire thought he should be sent to an institution, but Catherine believed it was important for him to remain near the university. Claire has little understanding of Catherine and regards her as mentally ill, but she means well and takes her family responsibilities seriously.

Hal, whose full name is Harold Dobbs, is a twenty-eight-year-old mathematician who teaches at the University of Chicago. He also plays drums in a rock band made up of mathematicians. Hal is a former student of Robert's, whom he admires immensely, not only for the brilliance of his achievements in mathematics but because Robert helped him through a bad patch in his doctoral studies. Hal first met Catherine briefly four years earlier, and when he meets her again, he tries to make friends with her. He seems rather shy and inexperienced with women, and it is she who seduces him rather than the other way round. After they spend the night together, he is ready to fall in love with her. Hal also confides in Catherine that he is dissatisfied with the progress of his career. His academic papers are being rejected by journals, and he feels that his work is trivial. Although he does not openly acknowledge it, this is one of the underlying reasons that he is examining Robert's notebooks. If he can discover something important, it will boost his career and perhaps make a name for himself. He is thrilled when he finds the proof in Robert's notebook and takes some convincing by Catherine that it is her work. This harms their relationship, since Catherine is annoyed that he does not believe her. When Hal is convinced, he reacts with humility rather than jealousy. He tries to repair their relationship and asks Catherine to go over the proof with him so he can ask questions and understand it better.

Robert was a famous mathematician who has just died of a heart attack in his fifties. He is already dead when the play begins, but he appears in the first scene in Catherine's imagination and returns in two later scenes, which flash back to earlier years. Robert was a mathematical genius. When he was in his early twenties, he made major contributions to game theory, algebraic geometry, and non-linear operator theory. According to Hal, his former graduate student, he invented the mathematical techniques for studying rational behaviour. While he was still in his twenties, Robert was afflicted by a serious mental illness, which dogged the remainder of his life. He became so incapacitated that his daughter Catherine had to stay at home to care for him. Robert had a deep affection for Catherine. He realized the sacrifices she made in caring for him, and he believed that she saved his life. Robert was also worried that she appeared to be wasting her life. Four years before his death, Robert's illness went into remission, and he was able to teach again for one academic year. During that year, Robert thought he was back at his best and would once more be able to do exciting, pioneering work in mathematics. He even asked Catherine if she would collaborate with him, but she soon found out that his notebooks were full of nonsense; his mind was confused, and he was lapsing into insanity.