A young woman works as a knife thrower and acrobat for a traveling circus. At four years old, her family's wagon was caught in crossfire, killing her parents and separating her from her two-year-old brother Triton. Cathy was adopted by members of her parents' circus and grew up with them. When Gundam pilot Trowa Barton asks to join, Cathy convinces the manager to let him in. She develops a big sister attitude towards Trowa, even after discovering he is the pilot of Heavyarms. Cathy also helps take care of Trowa's friends, such as feeding Wufei when he stays with the circus following the failed Treize assassination attempt, and caring for Heero after his self-destruct incident.
In MC0021, at the request of Instructor W, Catherine takes in a nameless boy who resembles her brother Dokter T. She trains him to be a mobile suit pilot and to adapt to atmospheres different from those on Mars. Additionally, she teaches him circus skills like knife throwing. Despite the passage of time, Cathy still has a strong temper, punching the boy upon their first meeting for not greeting her when he arrived.
