Joey is the leader of a heavily armed female biker gang. When she tries to rob an armored truck, she is thwarted by Ben as Fourarms. The remnants of one of Vilgax's defeated drones soon fuse with Joey and she becomes Rojo (Spanish for red), a powerful cyborg. The upgrade gives her the ability to fly, super-strength, and a pair of blasters attached to each shoulder. Vilgax is able to communicate with her through the parts and force her to track down the Omnitrix for him. Joey is turned back to normal when Upgrade shorts out the spare parts, after which Gwen knocks her unconscious for attempting a sneak attack on Upgrade. Rojo returns in "Ben 10 vs. The Negative Ten (1)" as part of the Negative 10, with alien tech presumably supplied by the Forever Knights. She has lost her red skin and drone eyes though and has a new cybrog suit. Her rival in this episode is found out to be Charmcaster. Joey is greedy, wild and amoral, and not hesitant to attack innocent bystanders just because they annoy her.
Joey/Rojo has only made two appearances in the Ben 10 Series.

Joey/Rojo's First Appearance
The Alliance