Cynthia Bridgitte Fitzgerald was a Neucom fighter pilot.
The daughter of a wealthy Usean family, she was raised in a conservative background along with her sister Fiona, adopting an elitist and professional view of life, compared to the carefree attitude of her sibling. In 2033, she earned a master's degree in Genetic Engineering at the Chopinbrook University, then joined General Resource for the next four years. She then transferred to Neucom as a scientist, becoming a chief consultant in the Neucom Emergency Unit and one of the leading researchers of the R-series of aircraft, operating under the TAC name "Priest".
Cynthia was first introduced to Nemo during the Intercorporate War in a videomail from Fiona after it saved the lives of her and UPEO's Gabriel Clarkson during their defection to Neucom, and became their commanding officer in NEU.
She is an advocate for the sublimination of humans  and defects to Ouroboros after a Neucom raid on a General Resource air base. The Sphyrna enters the battle zone and Cynthia, although clearly surprised by Ouroboros' early arrival, takes the opportunity to follow her dreams. This is much to her sister's distress, who remains with Neucom. Under this outcome of the simulation, Fiona and Nemo must face off with Cynthia in combat, whilst they are persuing the Sphyrna. Fiona is obviously hesitant to fire at her sister, leaving Nemo to to shoot Cynthia down. After Neucom defeat Ouroboros, Fiona receives a pre-recorded message from Cynthia. Cynthia mentions the wonders of the Electrosphere. Whether Cynthia was killed during her fight with Nemo, or whether she is still an AI running in the Electrosphere is not made clear.
Cynthia is mentioned in Photosphere, a 27 page booklet included with the Japanese release of Ace Combat 3: Electrosphere. This gives back stories to the major characters of the game; this is Cynthia's entry:
"Suppose there is constant danger to be found in our pursuit, with scientific and technical models, of that which we refer to as our 'potential.' In which case, it is only those who accept and acknowledge their own imperilment who are qualified to talk of the hidden potential of the electrosphere as if it were a wondrous dream or somewhat utopian. The coming world to which all shall presently proceed - yet, it is at this time still a domain composed of alien perceptions and feelings, where all is completely new, of which no one has yet experienced. If you insist that this place truly exists, then I would really like to know about it, to see it, to feel it. That's right. Even if the cost would be to endanger my body, I don't mind at all. Think about it. It is actually this flesh, necessary for us to live, that has imposed constraints on an existence so steeped in mystery as the soul and psyche. Have you never felt this? What I want is the ability to prise open the door to this new world. That and nothing else."
Although badly translated, it does give more insight into Cynthia's fascination with the Electrosphere.