After The Mad King's War ended and her father died, Fiona continued his legacy and sought to maintain her country's safety. Initially, she sides with the Begnion Occupational Army, though Jarod does not trust her. After seeing the Begnion Occupational Army hold civilians as hostages to make the Dawn Brigade surrender, Fiona defects and joins Micaiah's side. From this point on, she aids Micaiah in the liberation of Daein and remains as one of her soldiers during the war against the Laguz Alliance. Following this, she joins the heroes in their mission to defeat Ashera.
After the war, Fiona returns to Marado and continues to watch over her beloved people, protecting them until the autumn of her years.