Who is Beatrice Joanna-Foxe from The Wanting Seed and what is their importance?

Beatrice-Joanna Foxe has elemental traits, almost as if she were an archetype rather than a normal human. She is the Earth Mother, the fundamental life-giver, driven by an overwhelming urge to procreate. In that sense, she represents what is best in humankind, yet her focus on sexuality also leads her to stray from her husband into an affair with his duplicitous brother. Her infidelity and her lies about it cannot be explained as a reaction to her husband's romantic disinterest in her, because Tristram seems attentive to her throughout the time they are together. Beatrice-Joanna seems to thrive on sexual intrigue, and she shows little awareness of Derek's moral failings. Later, when she pines for Tristram, her emotion seems to be driven as much by boredom or a need for novelty as it is by deep feelings for him. The only intense loyalty she displays is toward her children. Heartbroken by the death of her first child, she is determined to carry her next pregnancy to full term, despite the dangers posed by her choice. She takes advantage of the shelter afforded her by her sister and brother-in-law despite the threat to their safety posed by her presence. When she emerges from hiding to present herself to Captain Loosely, it seems to be first selfless thing she has done, although it could be interpreted as a bold gamble to save herself and her twins. Beatrice-Joanna does not lack bravery or self-assertion, but she suffers from a moral blindness that works in sad counterpoint to her good traits. She is not an unlikeable person, yet she is flawed and untrustworthy, and there is no evidence at the novel's end that she has changed for the better.