Awesome Guy is a guy who is awesome, but will never be more awesome than The Awesome One. That's why he is his enemy. he is the awesome one's own brother.
He was just one normal lad, you know, not awesome. One day, he asked his brother if he could be awesome too and he said no. so he went to his room and became Awesome himself with help of his best friend, Robbie Rotten. After he became awesome, he argued with his bro about who is awesomer and awesome one killed him in the process. Robbie punched Awesome one in the face.
But a few weeks later, it turned out that he wasn't dead, He actually was hiding in LazyTown with Robbie. Now, Awesome Guy lives in LazyTown, avoiding his brother in Robbie's lair. He currently stars in the LazyTown (TV Show), so he's awesome enough.