 In Reverse / Rebirth , Riku has been transported from the realm of darkness and fights his inner darkness as he battles upward from the basement levels of Castle Oblivion . Vexen fights Riku to obtain his data and creates the replica of him to counter Marluxia 's plan . Ansem , who had previously taken over Riku 's body , tries to regain control of Riku , but King Mickey 's support keeps Ansem at bay . On the way , Riku battles and defeats Lexaeus , a member of Vexen 's circle , only to be dragged into the realm of darkness . However , he is saved by King Mickey when Ansem nearly succeeds in taking Riku 's body as his own . With Marluxia eliminated by this time , another of Vexen 's allies , Zexion , attempts to dispose of Riku by drowning him in light . Riku is saved by Naminé disguised as Kairi , who helps him to control his darkness , allowing him to defeat Zexion . Riku later meets DiZ , an enigmatic individual interested in Riku who sends him to find Naminé . Riku 's replica , who has since learned of his altered memories and seeks to justify his existence , fights Riku only to be destroyed by him . Riku chooses to face Ansem upon learning from Naminé that Ansem lives in his heart , and defeats him after DiZ summons him for Riku to fight . Riku then sets out on a journey to utilize both his darkness and his light with King Mickey as his companion . 
