Ona is a proud, haughty woman who is not allowed to get married. Because her father had no sons, she is supposed to give him sons to carry on the family line. She can have lovers and bear children, but she cannot get married.
As a result of the fact that she can't ever get married, she torments Agbadi, her lover. Her sarcasm and constant teasing keeps him interested. When he is almost killed in a hunting accident, however, Ona realizes what he means to her – and she spends the next weeks (or possibly months) nursing him back to health. Agbadi realizes then what he means to Ona, so he torments her back. That's when she becomes pregnant with Nnu Ego. She promises Agbadi that if the child is a daughter, he can have the girl. Ona does bear a daughter, Nnu Ego.
Ona and little Nnu Ego finally moves to live with Agbadi because it's clear that Nnu Ego's chi is the slave woman that died during Agbadi's senior wife's funeral, and Nnu Ego needs to be close to her chi's burial ground. Ona dies during childbirth in a subsequent pregnancy.