He is very arrogant, and he hates all kinds of fun. He is a bit of a loser. He especially hates The Annoying Orange. He also hates the Unicorns that Mordecai and Rigby led them to in their house because a long time ago, the same unicorns ruined Charlie's life.
And no, Charlie didn't bite some toddler's fingers.
His body is white and has a horn on his head.