A friend of Juan Rico, Carmencita Ibanez lived near Juan and his parents allowed her to use their swimming pool many times. Carmencita was the sort of woman who never settled into any relationship and Juan described her as having a different man around her constantly.
Carmencita decided to join the Federation to become a pilot in which she succeeds, which Carl and Juan who went with her inlisted into different Federal Military units. Juan had a crush on her, as she was his major inspiration to join the Federal Service.
She excels at Mathematics and gymnastics, and also becomes a pilot, since most of the pilots in the Federation are universally female, they are the perfect candidates for piloting and reasons of ethics and morale.
She is able to become an ensign in the Space Navy and a junior watch officer and pilot-under-instruction.
When Juan meets her after several years after their last meeting he is surprised to discover her head to have been shaved (which she had done for practical reasons in zero gravity).