Atticus Rhodes, known in Japan as Fubuki Tenjouin (天上院吹雪, Tenjōin Fubuki), is the missing brother of Alexis, who mysteriously disappeared into the old abandoned Obelisk Blue dormitory of Duel Academy.
In the Japanese anime, Atticus writes his signature as Fubuki 10Join.
Although Atticus hasn't made an appearance in the manga, he has been mentioned several times. He is a star duelist in the U.S.
(Source: Yu-Gi-Oh Wikia)