Who is The Wizard of Reckoning from Going Bovine and what is their importance?

The Wizard of Reckoning is the antagonist of the book. He is a large, mysterious knight who is chasing Cameron while he pursues Dr. X. The Wizard seems to want Cameron's life and shows up in the moments when Cameron's body is weakest. If Cameron is the Road Runner, the Wizard is the coyote. Cameron believes that he has conquered the Wizard, but finds out in the end that he can never outrun the Wizard. Why? Because Cameron IS the Wizard. The Wizard is the part of himself that Cameron has been hiding from.