For those who have not completed games in the Xenoblade Chronicles series, this page contains spoilers regarding the plot. Discretion is advised.
If Fortun was spared during Definian Downfall, she will be stolen/retrieved from New LA by a Definian named LV757: Lyvia and Erio in response will sent the player to retrieve Fortun from her, triggering the mission Fortun and Glory.
After the player hears of a mysterious woman that changed her appearance in the Administrative District, the player discovers that a woman known as "Avi" who was trying to buy weapons from a Grenada employee named Fritz is LV757: Lyvia in disguise and escapes after being confronted by the player.
After defeating LV757: Lyvia and recovering Fortun, she decides to start anew in New LA under the disguise of Avi and can be found on the bridge between the Outfitters' test hangar and the diner.