Unlike Plutonian, Max wasn't born with his powers. He paid a loopy scientist to give him the powers. The scientist isn't really interested in the people who come to him to get powers, just the money he gives them. As a result, most of his patients die. In fact, Max is his only known success, and that's because the scientist's assistant ran the experiment on Max instead. She actually paid attention to what she was doing.
Max is in Plutonian's home town when Plutonian goes off the deep end. Apparently this is because he told his girlfriend who he really is and she reacted by exposing his secret identity to everyone. Based on a story from Max's childhood, it seems Plutonian was unstable before that but hid it well in superheroics. I'll have to pick up the trades for Irredeemable at the point where I left off in the singles to see if there's more to it than that.
Max's world is turned upside down by Plutonian killing millions. If the most powerful person and unstoppable force for protecting the world is now destroying the world, what's a man whose nearly as powerful but has always been a force for chaos to do?
Max's answer is to become a protector. Problem is, he doesn't really know how to do that. He has no internal compass for what's the right thing to do. His method is to obey the letter of the law. Right from the start he gets his own gang arrested, burns all of his stolen wealth, and refuses to have sex with Jailbait any longer. He also tries to get Jailbait to a place of safety, which she sees as rejection altogether. He ends up picking up another sidekick who looks a lot like Jailbait but is older. Her entire family was killed by a racist gang that worships the rampaging Plutonian as a force purging the world of the unpure races. At first she masquerades as Jailbait but later she goes by Headcase.