Amitie Florian hails from the dying planet Eltria as the elder daughter of the Florian family, who stayed behind with hopes of reviving their world. Her father, Grants Florian, was a researcher whose collapse from illness fractured the family's dream. Ten years before the events in *Reflection*, when her younger sister Kyrie was six, nine-year-old Amitie already displayed traits inherited from her mother: striking beauty and red hair. These attributes, combined with Amitie's proficiency in completing tasks, ignited envy in Kyrie. This period solidified Amitie's proactive nature, driven partly by her desire to be a protective older sister, though her tendency to treat Kyrie as a child later fueled conflict.

Characterized as hot-blooded and tomboyish, contrasting Kyrie's demeanor, Amitie maintains a realistic view of Eltria's inevitable doom. This perspective leads her to oppose Kyrie's use of time travel and criminal methods to save their home. In the portable game continuity (*The Gears of Destiny*), Amitie exists as an android "Gears," traveling dimensionally to Earth to find Kyrie. Infected by a virus during an encounter, she allies with local mages including Nanoha Takamachi. She protects Kyrie from U-D, sustaining a broken arm, and later activates her device's Overblast function to halt the threat. After the conflict, she receives medical aid from the Time-Space Administration Bureau and assists Kyrie in rebuilding Eltria alongside allies like the Materials and Yuri Eberwein.

In the movie continuity (*Reflection* and *Detonation*), Amitie pursues Kyrie to Earth after failing to restrain her on Eltria. She intervenes to save Hayate Yagami from Iris and obstructs Kyrie's attacks on Nanoha Takamachi and Fate Testarossa. During a confrontation where Kyrie activates System Alter, Amitie counters with her Accelerator spell to match Kyrie's enhanced abilities but is gravely injured by her sister's gunshot. Following medical treatment and testimony at the Administrative Bureau, Amitie provides critical background on Kyrie's objectives involving the Tome of the Night Sky and the Examia crystal. She subsequently contributes to upgrading Raising Heart and Bardiche with Variant Core technology to grant them Formulan capabilities. In *Detonation*, she assists in the conflict against Phil Maxwell, notably thwarting his attempt to escape via a memory-carrying spacecraft.

Amitie utilizes the Formula Eltria magic system, specializing in ranged combat with her blue-framed Variant Zapper device, favoring gun-shooting proficiency over sword-fencing. In the movie continuity, her physical resilience is augmented by a blue Formula Suit. This suit amplifies her bodily functions, provides energy interference resistance, and includes a short-term power-boosting drive function. Her documented spell repertoire includes Vulcan Raid, Finest Cannon, Fencer Slash, Accelerator (enhancing her speed and combat effectiveness), shield generation, and the Heavy Edge upward slash.