Thelonious Viper Professor Thelonious Viper , known in Japan as Professor Cobra 「 プロフェッサー ・ コブラ 」 ( " Purofessā Kobura " ) , is a professor hailing from West Academy and the main antagonist for the first arc of season 3 . He was a former military commander who after losing his adopted son Pierce , allied with Yubel to revive him using the Bio - Bands to drain energy from the academy ' s duelists . After failing to defeat Jaden Yuki , Yubel changes his memories and then leads him off a ledge causing him to fall to his death . Biography . While performing military services in a war that ravaged his country , Viper came upon an infant whom he believed saved his life by drawing his attention away from an area which was suddenly detonated . In the English dub , it is simply stated that the rest of the unit he was with was ambushed and captured while he left them . He adopted the child , Pierce , and came to regard him as the " angel " in his otherwise torturous life . Years later , chasing after Duel Monsters cards given to him by Viper as a present that were swept up in the wind , Pierce was run over by an oncoming vehicle ( This scene was cut from the dub , here , he died of an illness ) . Later on , Viper entered Duel Academy in the third year and in a desperate attempt to aid Yubel ( who promised to raise his son from the dead ) , Professor Viper pitted students against one another in Survival Duel s . The only concern he had was that Adrian Gecko grew suspicious of him . Viper attempted to get rid of him by forcing him into Survival Duels and setting the Bio - Band drainage level to maximum in an attempt to kill him , knowing that Adrian would still Duel . However , Adrian forced Viper to lower the level when he got the entire Ra and Obelisk dorms to Duel at the same time . Adrian later manipulated Jaden and his friends to act as decoys while he infiltrated Viper ' s hideout for a card Viper had . When Jaden Yuki and his friends broke into Viper ' s hideout , Viper found that Yubel still needed more energy and faced off against Jaden in a Duel ( in the dub , part of the reason was that Yubel wanted to see Jaden suffer ) . When he lost , Yubel , manifesting in energy form as Viper ' s son , modified Viper ' s memories of Pierce ' s death , deceiving him into believing that Pierce never died . In a stupor , Viper followed his " son " to the edge of the platform where he seemingly fell to his death . ( In the US version : after Yubel grabs Viper ' s face , he simply disappeared , which heavily implies his death , though this is not specifically stated . ) After Jaden became The Supreme King , his words alongside Mr . Stein ' s linger in his mind , specifically about his not treating Duels as anything more than a game . Viper is seen one more time prior to Jaden ' s final Duel with Yubel as Jaden remembers all the people Yubel has wronged . Deck . Viper plays a " Venom " Deck , which allows for the distribution of " Venom Counter s " through his monsters such as " Venom Snake " and " Venom Boa " to an opponent ' s monsters as means of weakening and ultimately destroy ing them . Several of his monsters are based on the , a serpent - like race in and . One of these creatures , Viper ' s signature card " Vennominaga the Deity of Poisonous Snakes " , is able to circulate poison in the opponent ' s body upon inflicting damage , declaring an automatic victory for its owner within three turns .