Marx at first appeared to be harmless, but was a skilful manipulator bent on world domination.
Marx at one point caused the Dream World's sun and moon to battle with each other, then requested that Mezzo and Ever seek out a wish-granting comet to resolve the issue. Once they did so, he knocked them aside, and made a wish to rule the Dream World. The comet agreed, evolving him and granting him improved powers. Mezzo and Ever fought him in battle, and he was presumably killed in the aftermath.