Jo is seventeen and an only child. At the beginning of the play she has decided to drop out of school. Indeed, she has changed schools so often, she has never had the chance to learn anything useful, though she does display a natural artistic talent. Jo also has a sharp and acerbic wit, usually employed to chastise Helen, who can be equally venomous.
Raised by a highly promiscuous mother, Jo is curious about sex, but does not share Helen's more natural inclination toward it. She is 'ruined' by a sailor, Jimmie, who proposes marriage, but never returns.
Also left alone by her mother, Jo decides to live with Geof, a homosexual friend who helps her through this difficult time. Their harmony is ruined by Helen, who returns to 'look after' her daughter, and then promptly leaves.
Helen is Jo's mother and, though never explicitly said, works as a prostitute. She is around forty years old, though evidently looks younger. She is stunningly selfish and, we learn, regularly leaves her only daughter around Christmas time to be with one of her fancy men.
Helen is an alcoholic and is in an abusive relationship with Peter, a bookmaker, younger that herself. She marries him later in the play and we learn that this is not her first marriage. The first was to what she describes as a 'puritan'. Helen's sexual appetite was fulfilled by an extramarital affair with an 'not very bright Irishman', Jo's father.
Despite these myriad character faults, occasionally Helen's love for Jo shines through. She does love Jo. But she loves Helen more.
Geof is a young friend of Jo's and an art student. As we meet him in Act 2, he seems to be angling for a place to sleep, though he denies it. Jo guesses that he has been kicked out by his last landlady, due to his overt effeminacy. Though Geof is gay, he remains somewhat asexual during the course of the play, despite attempting to kiss Jo, awkwardly.
Geof is a true friend to Jo. He pays the rent, cleans the flat and sources necessities for the impending childbirth. He finds Jo work and lifts her moods when she is down. He wants to be involved in the birth and to help bring up the baby.
Geof avoids confrontation and is bullied by both Peter and Helen at times. In the end, Geof is forced away by Helen, leaving Jo without a friend.
Peter is Helen's younger boyfriend and later, husband.
Peter only has one eye, having lost one as a private in the army. There are several references to blindness in the text, but most notably from Peter as he tells the story of Oedipus, the Greek who married his mother....perhaps a symbolic reference to Helen, who may remind him of his own mother.
Peter is wealthy, though he only splashes his cash on himself and Helen. He refuses to help the desperately poor Jo with either shelter or money.
Jo is sharper than Peter, often gaining the upper hand in their dealings. She exposes the many pictures of other women he carries in his wallet. It comes as no surprise that Peter eventually drops Helen for another lover.
Jimmie is a twenty-two year Navy sailor, and formerly a male nurse. He is Jo's boyfriend in Act 1, before he ships out for six months and never returns.
Jimmie seems to have a genuine affection for Jo, despite proving to be unreliable. He is honestly surprised to see that Jo has no hesitation to be in a relationship with a black man, the first (white) girl he ever met who feels that way. He teases her about his ancestry, from 'Cardiff', as opposed to an exotic tribal lineage. Later, Jo herself refers to him as a fantasy figure, Prince Ossini, though relents that he was merely Jimmie, a boy she knew no longer than a dream. He proposes marriage to Jo with a ring he bought in Woolworths - a discount department store, and gives Jo a toy car he carries. This exchange shows the childish level of responsibility later realised through his absence.