Cissy is one of the girls on Sandymount Strand in Episode 13, "Nausicaa." She is there watching over her two younger brothers, Tommy and Jacky. In the scene, she comes across as a light-spirited fun-loving girl. At one point, she goes over to Bloom to ask what time it is, and he appears a bit ruffled. Throughout the scene, she occasionally speaks roughly, and while the other girls are embarrassed, she seems not to care. The narrator once refers to her as being sincerity itself. Insofar as the episode is aligned with Book 6 of the Odyssey, Cissy corresponds to one of Princess Nausicaa's handmaidens.
Cissy also appears briefly later on, in "Circe." She is flirting with two English Privates, and when Stephen drunkenly bumps into her in the street, she becomes the cause of a fight. Bloom tries to get Cissy to intervene, but she is extremely flattered that the two men are fighting over her. At the last moment she tries to calm down Private Carr, but he is already too worked up and hits Stephen anyway.