Gia Mahan was a character on the TV sitcom Full House played by Marla Sokoloff.

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 a make-out party Gia hosted when her mother wasn’t around.

And yet, like Kimmy by D.J., Gia was shaped by Stephanie. An unknown time after her parents had been through a divorce, Gia is shown as a smoking, rebellious girl with horrible grades. She is possibly at least a year, maybe two, older than Stephanie, as a comment by Michelle - "Are you ready for your third year of seventh grade" - and her horrible grades the previous year indicate she might have been held back one year. And yet, as of early season 8, we learn that because of Stephanie, Gia has stopped smoking, she is more respectful to her mom, and her grades have improved.

Gia is a leader in some ways, as well, and performed in a band with Stephanie and Kimmy that failed miserably because the girls paid more attention to their appearance than to rehearsing. While a relatively minor character, her 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 very serious problems. Gia might have led Stephanie into some temptations, but by the end of the series, it was apparent that it would be Gia who would slowly be molded by Stephanie into a responsible young woman.