Leon is a very famous duelist who has won many tournaments. Since he was young Leon has always been fond of fairy tales and even wrote a letter to Maximillion Pegasus, requesting that he make Fairytale Cards. He has created a very powerful deck as a result. Leon has also always admired Yugi, and aspired to one day duel against him.
During his duel against Yugi in Kaiba's KC Grand Championship, he is revealed to be Siegfried von Schroider's younger brother, with his true name being Leonhart von Schroider. Leon's family never paid very much attention to him when he was a kid. They were always focused on preparing Siegfried to take over the company, and they would punish him for distracting Siegfried from his studies. Once learning of his strength in dueling and how good with computers his younger brother is, Siegfried finally acknowledged Leon and asked him to collaborate, to take down Kaiba corp.
