- "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)
Gia might be considered Stephanie’s Kimmy. Just as D.J. lets Kimmy lead her astray a little at times, Stephanie gets involved in a small number of wild, irresponsible things because of Gia, such as joyriding and attending Gia's make-out party when her mother is not home.
And yet, like Kimmy by D.J., Gia is 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 (in "Fast Friends") that she had two years of sixth grade. Her horrible grades the previous year indicate she might have been held back at least once. In "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 has her own clique of girls that she is the leader of, and would relatively boss them around and decide what they would do. Nobody seems to have the courage to stand up to Gia, except for Stephanie, and she earns the respect and friendship of Mickey.
Gia shows the full extent of her cruelty when (in "Is It True About Stephanie?") Stephanie refuses to break off her date with a guy named Jamie, whom Gia was interested in. When Stephanie retaliates, she hurts Gia's feelings, which prompts Stephanie to apologize. While Gia still considers Stephanie a dweeb, they soon become best friends.
In "We Got the Beat", she briefly performs in a band with Stephanie and Kimmy that fails miserably because the girls pay more attention to their appearance than to rehearsing.
Despite being a relatively minor character, Gia's presence shows that Stephanie, while lacking the control of the book series, still is 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 is apparent that it is Gia who is 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 seatbelts, as Danny explained to Stephanie).
In "All Stood Up" (her final appearance in the series), 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.
- used to ditch school numerous times and got her "friends" to ditch too
- acts the way she does because she is upset about her parents divorcing
- is similar to Bobby Popko as they're both wild and put themselves and their friends in danger
- "Girl Talk" (2.7)
- "Surrogate City" (3.14)
- "Best Summer Ever" (3.1)
- "Say Yes to the Dress" (3.7)
- "Happily Ever After" (3.16)
- "No Escape" (4.5)
- "Driving Mr. Jackson" (4.8)
- "The Prom" (4.12)
Gia returns in the episode "Girl Talk". She is revealed to be a soccer mom and walks for nine different charities, though D.J. later mentions that she thinks Gia can't even name the charities she claims to walk for, and that she just does it for the exercise.
Gia is also Rocki's mother and later Matt's new girlfriend as of No Escape.