Dox Dox , known as Kyū in the Japanese version , is the younger of the two Paradox Brothers . He and his brother Para Duel as a tag team , and appear to Duel the protagonists in both " Yu - Gi - Oh ! " and " Yu - Gi - Oh ! GX " . Dox has the kanji for half of the word " Labyrinth " on his head , with his brother ' s head having the other half . Biography . Yu - Gi - Oh ! He and his brother were hired by Maximillion Pegasus to work as Eliminator s in his Duelist Kingdom tournament . The two duel as a team , with their " Labyrinth Wall " card enabling them to change the playing field to resemble a complicated underground labyrinth , making gameplay more akin to a board game than a card game . The two guard an underground area of the island . It is here that they meet Yugi Muto and Joey Wheeler , who must defeat them in order to pass and move onto Pegasus ' castle . They begin a Tag - Team Duel against one another , and the Brothers have a cohesive strategy , with their Decks built to play off of each other ' s . In addition to changing the gameplay , the brothers ' Decks focus on the Summoning of their powerful " Gate Guardian " monster , by gathering its component pieces onto the field . Though they come close to victory , the brothers are defeated when Yugi fuses his " Summoned Skull " with Joey ' s " Red - Eyes Black Dragon " with " Polymerization " to form " Black Skull Dragon " , whose ATK was able to surpass that of their " Gate Guardian " when Joey uses his " Copycat " card to use the brother ' s own " Riryoku " against them . With their victory , Yugi and Joey both obtain enough Star Chips to gain entry into the tournament ' s final rounds . However , the Brothers still have another test that Yugi and Joey must pass . They inform them that one of the doors that leads out of the room will let them leave the caves , while the other simply leads to an endless maze . The brothers claim that from here on out , one of them will speak only lies , while the other will speak only the truth . Yugi realizes that both brothers are in fact lying , and they even have the ability to change which path leads where . They are tricked into admitting this via the use of a two - headed coin , and Yugi and Joey are able to move on . In the epilogue of the series , which is cut from the dub , the brothers are seen dueling Mai Valentine and Vivian Wong on top of the . Yu - Gi - Oh ! GX . The Brothers are hired by Dr . Crowler to Duel Jaden Yuki and Syrus Truesdale , who will be expelled should they lose , due to their trespassing at the Abandoned Dorm . The Duel is conducted in a more normal fashion this time , with the two Dueling using standard Duel Disk s . Their strategy still involves the Summoning of " Gate Guardian " , but they also reveal an even more powerful force - " Dark Guardian " , who can only be Summoned upon the destruction of " Gate Guardian " . The brothers focus their efforts on Syrus , believing him to the weak link of the opposing team . This is very successful , but Jaden eventually gives Syrus the confidence to continue , and the brothers are once again defeated when their opponents pool their resources to Summon a Fusion Monster . This time , Syrus uses his " Power Bond " card to fuse his " UFOroid " with Jaden ' s " Elemental Hero Tempest " , forming " UFOroid Fighter " , making its 4000 ATK points double to 8000 , which was enough to attack " Dark Guardian " and wipe out the brothers ' Life Points , even though it cannot be destroyed by battle . Other appearances . In " Yu - Gi - Oh ! GX Tag Force " , the Paradox Brothers participate in the Tag Force tournament . After completing the game once , the player may partner with either of them , and they can be found during part one of the game on the cliff . Upon acquiring his Deck Recipe , Dox also gifts the player with a " Labyrinth Wall " card . Voice / mannerisms . In the dub , the brothers speak using Chinese accents and almost exclusively in rhyme , with one brother finishing the sentence the other began . Deck . Anime .