Prometheus

Prometheus (プロメテ, Puromete) is a mysterious character from Mega Man ZX and Rockman ZX Advent. He and his partner Pandora are servants of Model W. He wields a beam scythe and uses fire-based attacks in battle.

Personality
Prometheus is a very arrogant fighter who enjoys nothing more senseless killing and a good battle. He also seems to hold a grudge against Vent/Aile and refers to him/her as a pawn in his game. His personality has yet be further explored, as his connection to Ashe.

Mega Man ZX
So time prior to the game's actual events, after Serpent had excarved the Biometals Model H, Model F, Model and Model P, Prometheus and Pandora approached Serpent and after their meeting, several company workers mentioned that both Serpent and Slither, Inc. had changed their way of business.

Prometheus, along with Pandora, worked for Serpent in order to reawaken the dormant Model W. Prometheus encountered Vent/Aile in one of the stages and retreat upon defeat and latered appeared again, this time teaming up with Pandora to fight the player. After both of them were defeated, they disappeared again and weren't seen again, not even to assist Serpent in his battle with Vent/Aile, apparently because he had already fullfilled his role in the game of Model W.

Rockman ZX Advent
Not much is known about Prometheus' role in the upcoming Rockman ZX Advent, only that he appears to be looking for Model A, has a mysterious connection to Ashe and apparently separated from his partner, Pandora.

Trivia

 * In Greek mythology, Prometheus was the Titan who created man from clay in the image of the gods and later gave man fire to survive. Prometheus was punished for this by being shackled to a mountain peak and having an eagle pick at his liver for eternity. Man was punished by receiving Pandora and her opening her jar/box.