Prometheus

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

Personality
Prometheus is an arrogant fighter who enjoys nothing more than senseless killing and a good battle (Ironically, when Ashe/Grey defeats him and his sister, he hints that his having to do senseless fighting was one of the reasons as to why he and his sister wanted to betray and kill Albert in the first place.). 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
After Serpent had excavated the Biometals Model H, Model F, Model L and Model P prior to the games events, Prometheus and Pandora approached Serpent. Several company workers mentioned that after their meeting, both Serpent and Slither, Inc. changed their way of business.

Prometheus and Pandora worked with Serpent in order to reawaken the dormant Model W. Prometheus encounters Vent/Aile in Area X, only to retreat upon defeat and reappear with Pandora at Area O. After both of them are defeated, they disappear until ZX Advent.

Mega Man ZX Advent
In ZX Advent, it's revealed that Prometheus and Pandora are sibling Mega Men, "DAN-001" and "DAN-002" created by Master Albert to further the Game of Destiny. Albert intentionally created with repeatedly short life spans so that they would not be able to betray him. Prometheus kills Albert's decoy at the Submerged Volcano in the mistaken belief that it was Albert. However, he and Pandora continue to proceed with the Game of Destiny in the hopes that they can take Albert's place, and attack Grey/Ashe. After Grey/Ashe defeats the pair, Model W absorbs their souls and the real Albert appears. The volcano begins to collapse, and Grey/Ashe is unable to rescue them. Despite the falling of a volcano on them they may not be dead. It seems not everyone who gets energy absorbed by Model W dies. In the first ZX Vent/Aile have power absorbed by Serpent's Model W but did not die. They are not refered to during the rest of the game, and Albert doesn't ressurect them like he did the others. All of this, plus the fact that their bodies don't disappear into thin air, suggests that they may still be alive.

Trivia

 * In Greek mythology, Prometheus was the Titan who created man, gave them fire, and taught them how to trick the gods in order to get the better half of a sacrifice. Prometheus was punished for this by being shackled to a mountain peak and having an eagle pick at his liver for eternity. His brother and mankind was punished by receiving Pandora and the evils she unwittingly carried in her box.
 * In Bob and George, in the future "X Era" Proto Man takes up the name Prometheus.