This sounds best imo. Maybe they could be with him and turn on him when colorguy gives 'guidance' or whatnot.
So here's what I think.
While Color guy walks down the street, he turns around. He sees a crowd of gray people.
He then walks through the crowd, and close to near where he entered. Then he turns around again and talks to the gray people, still following him. He asks them why they're sad, they say it's because the evil guy. As they are talking, evil guy says something. He is behind color guy. Color guy stares at evil guy. He turns back and nods at the gray people. Then, they all charge and kill evil guy.
Then color spreads :D
oh and they make a statue of color guy?