|Affiliation and military information|
|Affiliation||Anatolia (Armored Core 4)|
Line Ark (Armored Core: For Answer)
|Occupation||Operator(Armored Core 4)|
|Conflicts active||Lynx War|
|Notable battles||Battle at the Abandoned City|
|Real world information|
|Appearances||Armored Core 4|
Armored Core: For Answer
Armored Core: A New Order of "NEXT"
Armored Core Designs 4 & for Answer
|Voice actor||Maaya Sakamoto (JP)|
Kari Wahlgren (ENG)
The daughter and only child of the renowned Professor Jarnefeldt, Fiona ends up saving the man who would become Anatolia's Mercenary and take him to Anatolia. She later becomes his Operator after her father's death. Despite this, she shows considerable guilt in using the Raven to sustain Anatolia, and later develops romantic relations with him.
After the mission Seed a Barren Earth, she takes the Raven and leaves Anatolia. She makes a short return in Armored Core: For Answer, returning as the Operator of the Raven now working for Line Ark. Her fate after the battle at Line Ark is unknown.
Unlike Emil, Fiona is shown to be somewhat naive and optimistic for her age. Although she does assist in sending the Raven to kill other Lynxs or destroy targets, Fiona often questions the need to do so and demonstrates sorrow and regret during mission endings.
Fiona experiences a notable change in character over the course of the campaign in Armored Core 4, most notably towards Anatolia's Mercenary. In the beginning, she is more distant and professional. However, over the course of the story, Fiona displays relief at the protagonist's well-being after each mission. Her tone also changes to become more concerned of his well-being, especially after he is forced to fight 4 Originals by himself during the final moments of the Lynx War. It can be believed that she begins to feel guilty for forcing the protagonist to fight, based on her words spoken to the Protagonist throughout the game.
By the time of Armored Core: For Answer, she is shown to have matured considerably and lacks the innocent and naive personality displayed during the events of Armored Core 4.