I enjoyed Restart by Gordon Korman, which does, indeed, have a bully for its main character. Chase is the full on stereotypical athlete bully. But is he really? Because when we meet him, he's suffering from amnesia after a head injury. He's not aware he's a bully. The people around him certainly are. The story is told from different points of view, including those of people he has bullied and those of his bully friends.
The reality of his pre-injury life is only slowly revealed to Chase. He is shaken by it. He doesn't want to go back to who he was.
That's a nice redemption story. I like redemption stories. It is also hopeful for readers, because it suggests bullies can see the error of their ways, though maybe only after something dramatic like amnesia.
As a well-known over thinker, though, I wonder about the science behind amnesia and whether or not a personality would change this way and this much. Would the bully slowly return? And would that not make an interesting story, too? A dark, disturbing one?
Maybe that would be an adult book.