Auto-Fiona (referred to only as "Fiona Fox" or "the Auto Automaton") was an Auto Automaton built by Dr. Ivo Robotnik based on a young Mobian vixen named Fiona Fox, who was being held as a prisoner by him in a mine at the time. The Automaton was activated years later by her creator to trap the heart of Miles "Tails" Prower in order to roboticize him, but while attempting to drown Tails after the plan started going wrong, Auto-Fiona became rusted in the water and was paralyzed. Tails later left Auto-Fiona on the island he'd found her on as a monument to his lost youth and Auto-Fiona appeared to let out a tear as she watched him leave the island.
Auto-Fiona was skilled at manipulation judging by how easily she had Tails fall in love with her, and she also had super strength and could use melee weapons such as clubs. Her only known and major weakness was the fact that she wasn't waterproof and rusted very easily after a short period of time. Although, she was still able to drink liquids and not become rusted. Like the real Fiona Fox, she had dark red fur and blue eyes.