Gerty MacDowell is a young girl who is lame in one foot. Her big role comes in "Nausicaa" when Leopold Bloom masturbates to her while she lies on the beach and daydreams about men. We learn that Gerty was recently thrown off by a boy, Reggy Wylie, and that she is pining for him. Gerty also suspects that her girlfriends, Edy Boardman and Cissy Caffrey, are jealous of her beauty and try to spite her. When Gerty sees the dark man (that is, Bloom) she begins to imagine him as a romantic figure and tries to think of how they might meet each other.
In "Nausicaa" Gerty comes across as a fairly simple hormonal young girl. Though we do get a window into her thoughts, the novel is not as sympathetic to her as it might appear to be. The problem is that the narration in the episode is written in extremely sentimental parodic prose. As we try to treat Gerty as a character, we have to remember that whatever idea we have of Gerty is being filtered through parody.
What is clear, however, is that Gerty is very aware of how she appears to other people; she knows how she wants to be perceived. Whereas Bloom is hiding behind a rock in the episode so as not to be seen masturbating, Gerty can tell that he is enthralled with her. She suspects that he may be masturbating, and lets down her hair and raises her skirts so as to arouse Bloom. She also is careful not to reveal that she is lame until she has to. In short, Gerty may be a love-crazy young girl, but she is not quite as innocent as one might think.
In some ways, Gerty's monologue anticipates that of Molly Bloom at the close of the book. Before Molly, Gerty is the first extended female point-of-view that we get in Ulysses. Yet after reading Molly's monologue, it becomes very clear that the female point-of-view that is being exalted is that of an older and more mature woman, one whose disappointments are more complex than being thrown off by a young love.