About
Dr. Doppler is a Reploid scientist. Originally a benevolent researcher and supervisor of Dopple Town, he is the creator of the Nightmare Police and counter-measures against the Maverick Virus and irregular behavior in Reploids. He is also the discoverer of the Sigma Virus, for which he was developing a special vaccine. One day, pacified Mavericks went berserk and organized into the Doppler Army under Doppler's direction, which revealed that their return to normal had been a ruse, Doppler was Maverick himself, and his public anti-virus was a placebo. He even resurrected and upgraded Vile and Sigma as part of this plot.
(Source: Mega Man Knowledge Base)
