A two-parts story...
His superiority came from a great amount of greater and lesser qualities that were also found in others. But beyond all these qualities, there was one that mostly stood out and that was his wisdom. For whatever reason he could see the world different from others. He could understand things differently, see everything in a different light and in the end he managed to judge everything in a better way. Or so he thought.
He was not necessarily better than anyone else for he was not born to be perfect. Perfection was a goal that maybe he could have achieved, had he wished for it, but by all means - that was not his goal in life. His goal was far simpler but far more difficult to achieve. He was given a free mind, a free will and the potential to do anything he wished to. And the world was placed at his feet for him to follow his own path.
He was full of flaws but most importantly it was that he knew all about them. He would always recognize his mistakes, his weaknesses and he would draw different teachings from his own actions in order for him to be better. His own path was characterized through all the decisions good or bad that he made. And that's how he lived, always trying to feed his hunger that came from his passion. But nothing was that simple.
Because life was filled with more than his passions and wishes that just waited to be fulfilled and discovered. No. He also had to deal with people. And he was happy for it because others seemed to be and look just like him. And for some time he really felt like he belonged. Unfortunately his true nature would show up eventually and his wisdom would get the better of him, taking him in places where others could not follow.
Some understood him but others despised him, isolated him, making him feel out of place and alone. Mankind had its flaws, one of them being that they were meant to hate whatever they could not understand. And so our hero often felt alone for he really was. He began to realize that this world that was given to him was not meant for him at all and that maybe he did not have a place in here. With nowhere to go he could only isolate himself from the others, being careful to sometimes interact for the sake of it while feeding off his passions that made him special but that also killed him from the inside.
His creator watched how unhappy and lost our hero was. In a fit of anger he cast him away, considering him unworthy and being mad of his inability to adapt to this world that was created for him. The creator did not realize that the flaw was in himself and that the genius that he thought he had created had to be alone forever because of his wisdom. Because that made him out of the ordinary, out of the world.
Our hero had to leave the world and spend alone all the time that it was given to him, suffering because of his unfair fate. More than that, he became a symbol for the ordinary men. He became the avatar of everything that was bad and evil.
Such concepts do not born out of nowhere but are created by others and given away. And so did your hero became wretched, evil because of the world that was originally meant to have him. Mankind despised him without really remembering why, destroying his destiny forever.
They even gave him a name.