When her father grew ill, Gillian took over as the manager of the Windfall Café. Also, she at one point had a boyfriend, but this information has been declared "Top Secret", and she will not speak to Link about it. As a matter of fact, when Link talks to Gillian she will often tell him to leave, but if he talks to her at night and then plays the "Song of Passing", she will tell Link that she thinks the café gets a bit crazy at times.
It is possible that Gillian was once or still is close friends with a Fishman. When fed All-purpose Bait, one Fishman will talk about how he used to gaze at the lighthouse with "dear Gillian."