Gia might be considered Stephanie’s Kimmy. Just as D.J. let Kimmy lead her astray a little at times, Stephanie got involved in a small number of wild, irresponsible things because of Gia, such as joyriding and attending Gia's make-out party when Gia's mother was not home.
And yet, like Kimmy by D.J., Gia was shaped by Stephanie. During an unknown time when her parents had been through a divorce, Gia is shown as a cigarette-smoking, rebellious pre-teen with horrible grades. She is a year older than Stephanie, as evidenced by a comment she made that she had two years of sixth grade in the season seven episode "Fast Friends". Her horrible grades the previous year indicate she might have been held back at least once. In the season eight episode "Making Out is Hard to Do, Gia's mother Claire tells Danny that because of Stephanie, Gia has changed for the better by quitting smoking, becoming more respectful, improving her grades and losing her inclination to play pranks on others.
Gia can be described as a leader in some ways. Before becoming friends with Stephanie, she had her own clique of girls that she was the leader of, and would relatively boss them around and decide what they would do. Nobody seemed to have the courage to stand up to Gia, except for Stephanie, and she earned the respect and friendship of Mickey.
In "Is It True About Stephanie?", Gia showed the full extent of her cruelty when Stephanie refused to break off her date with a big Gia was interested in. When Stephanie retaliated, she hurt Gia's feelings, which prompted Stephanie to apologize. Well Gia still considered Stephanie a dweeb, they soon became best friends.
She briefly performed in a band with Stephanie and Kimmy that failed miserably because the girls paid more attention to their appearance than to rehearsing.
Despite being a relatively minor character, Gia's presence showed that Stephanie, while lacking the control of the book series, still was responsible enough, and driven enough, to be a great role model to a girl who was going through some personal life issues. Gia might have led Stephanie into some temptations, but by the end of the series, it was apparent that it was Gia who was changed for the better by Stephanie.
In "Stephanie's Wild Ride", she and Stephanie meet two boys at the mall, and the boys take them out for a drive. When Stephanie is invited for another drive, D.J. stops her from going. Later Stephanie finds out that Gia got into a car accident, along with the two boys. They are all injured, but thankfully, they survive (while wearing their seat belts, as Danny explained to Stephanie).
Gia last appeared in the episode "All Stood Up". She is first seen encouraging Stephanie to ask her hunky classmate Ryan to the dance. Then, at school, after Stephanie tells her about what Ryan did, Gia replies, "I can't believe that track troll stood you up". Later, Gia comes over to the house and tells Steph she has to talk to her; when Steph tells her that Ryan apologized, Gia replies, "I know. The whole school knows", and then goes on to tell Steph about the rumor that was spread around that consisted of Danny chasing Ryan down the hall and clobbering him with a canned ham before shoving him in a locker. Danny corrects her, saying it was spam; when Stephanie gets the truth about what really happened out of Danny (including that he told Ryan she cried), she says that she wants to transfer. When Danny thinks that means changing schools, Stephanie corrects him, saying she wants to change dads. After Danny leaves the room and Steph says that she has to go out with a guy who apologized to her just because Danny threatened him, Gia says, "Wait. Who says you even have to go?" Stephanie agrees and says that neither Ryan nor herself want to be there, so she will do them both a favor and stand him up. Gia nods, and she and Stephanie head over to the stairs, discussing what to do next. After "All Stood Up", Gia is not seen or mentioned again.
- "Fast Friends" (7.5)
- "Is It True About Stephanie?" (7.14)
- "Breaking Away" (8.2)
- "Making Out is Hard to Do" (8.3)
- "Claire and Present Danger" (8.8)
- "Stephanie's Wild Ride" (8.9)
- "We Got the Beat" (8.18)
- "All Stood Up" (8.22)
- It is noticed that she hopes that Danny Tanner and her mom Claire, get married
- She used to ditch school numerous times, and got her "friends" to ditch too