A replica of Riku created by Vexen from the real Riku's data.
Through Naminé's power he was infused with false memories and made to believe he was the real Riku.
The truth has wounded him deeply.

P E R S O N A L I T Y

The Replica was more aggressive and protective than Riku. A key difference between the two is as follows: while Riku fears the darkness in his heart, the Replica embraces his and wields it effectively. He was also more stubborn, which made him more of an enemy in the game. Another factor is how he searched for his existence nonstop. He seems to (like Sora) get very angry when he's confused, as shown when the Organization members such as Larxene try to trick him. At the end of his life, the Replica becomes much more like the original, turning sullen and mellow. He often lashed out at anyone who talked back to him, even if they overpowered him. He seemed to be as powerful as Riku was at Hollow Bastion, when Riku was under Ansem's possession.

The Replica clearly seemed to possess true emotions, as he seemed to harbor a close friendship or even outright affection for Naminé, though his belief in it was merely part of the illusion Naminé had created by tampering with Sora's memories while at Castle Oblivion.