Quistis wears a salmon zipped vest, with a gold-rimmed fold-over collar, that is zipped just below the ribcage exposing her midriff. She wears brown arm warmers and brown gloves, a long salmon skirt with a silver waistband, black pants, a brown belt and black shoes. She has blue eyes and wears her blond hair tied up held with a silver comb accessory, and has two long fringes framing her face. As an instructor in Balamb Garden she wears her SeeD uniform and a pair of silver-rimmed glasses.
Quistis is known as a child prodigy around Balamb Garden. At the age of 15 she became a SeeD, and at 18 is the youngest instructor in the Garden. She is less strict than the other instructors, leading some of her students to not take her seriously and to treat her with disrespect. Quistis tries to maintain her calm and due to her quiet assertiveness, stoic nature, and restraint, she mulls over her worries alone, kept at a distance from her pupils by her rank.
Quistis is an eighteen-year-old instructor at Balamb Garden, where Squall, Zell, and Seifer are students. She uses a chain whip in battle, and her Limit Break, Blue Magic, a common ability found throughout the Final Fantasy games, allows her to imitate monsters' attacks. Early in the game, Quistis is discharged as an instructor because she "lack leadership qualities". Afterwards, she maintains a more informal relationship with the other characters as a fellow member of SeeD.
As a child, Quistis stayed at an orphanage with most of the main characters. She then lived with foster parents, with whom she never developed any intimacy, before moving to Galbadia Garden at age ten. She became a SeeD at fifteen and an instructor two years later. Quistis initially joins Squall to prepare him for his upcoming field exam. She later takes Squall into her confidence and tells him personally about her demotion. As a result, Squall stops paying attention to her, which leads to Quistis asking if he is paying attention. Squall rudely tells her to go "talk to a wall", a famous comical line in the game, and not to burden him with her problems. This furthers the player's perception of Squall's awkwardness and anti-social tendencies. When Irvine refreshes the main characters' memories about the orphanage, they remember that Squall's asocial behavior began when Ellone, an older sister figure to Squall, left the orphanage unexpectedly.
They invade the Lunatic Pandora and fight through Seifer and defeat Sorceress Adel, making Rinoa Heartilly the only sorceress left in their era. As Ultimecia possesses Rinoa, Ellone sends her mind back in time starting the time compression. By believing in each others' existence the group survives its effects and travels to the future where Ultimecia awaits allowing them to defeat her. Upon Ultimecia's demise the time compression spell breaks and the timeline begins to revert to its original form. The group is momentarily trapped in a time warp, but due to their belief and reliance on each other they return to their time safely. As Balamb Garden celebrates the victory over Ultimecia, Irvine and Selphie record the festivities as Quistis greets the attending Edea and Cid, is unimpressed by Irvine's advances, and helps Zell when he almost chokes upon consuming too many hot dogs.
- When designing the characters, Nomura had wanted at least one female character to wear a skirt. Quistis was originally supposed to fill this part, but Nomura decided a long skirt worn over pants would look better. The role was eventually passed to Selphie. Nomura was surprised when the writers cast her as a teacher, despite being around the same age as the rest of the group.