Jill begins the novel as a nurse, a professional nurturer. When she meets Mike, though he is not ill, he is in need of a guide and a protector, and Jill fills these roles comfortably. She is not shy about her sexuality and in the very first sentence she appears in tells us that "her hobby was men," so she is also a fine teacher for Mike's education in the bipolarity of the human sexes, which Mike ultimately comes to regard as humankind's greatest gift. She is the first woman Mike ever sees, the first woman he shares water with, and the first woman he kisses. She may or may not be the woman to whom Mike loses his virginity—the identity of that woman is left ambiguous. As such, there is a deep bond between them that remains until the end of the novel, even when Mike has taken on many other water-brothers and lovers. It is her compassionate attachment to Mike, borne of their first encounter, which leads her to stick close to him, and grow and change with him throughout their journeys. Though Jill begins sexually liberal, Mike's penchant for constant nudity and eventually group sex require her to broaden her horizons further—steps that she would only take alongside Mike, whom she trusts absolutely. Though Ben is fixated upon her and wants a traditional marriage with her, he senses that her compassion for Mike is too deep for him to be able to compete.