Riku Replica is a Replica made of data from Vexen's research of Riku who appeared in Kingdom Hearts: Chain of Memories and acts as an antagonist in Sora's story and Reverse/Rebirth (Riku's story) while they were in Castle Oblivion. Though he almost always appears in Dark Mode, the only time when he did not have this suit on is his debut in either storyline. Originally a subject to test the real Riku, the Replica was later exploited to become a puppet of Marluxia who attempted to use him to manipulate Sora and overthrow the Organization.
In Kingdom Hearts[]
Kingdom Hearts: Chain of Memories[]
The Riku Replica was created by Vexen in order to gauge Riku's strength, and hopefully cause Riku's heart to return to the Darkness. At first Riku was shocked to see his counterpart, however, after the original heard the Riku Replica's taunts, a battle began. Due to the short time of Riku Replica's existence, he lacked experience and was quickly defeated by the original. Riku then attempted to destroy the Replica, but failed when the Riku Replica utilized the power of Darkness.
Riku Replica escapes, and eventually ends up in the Organization's chambers, where Larxene taunted Riku Replica over his loss. However, the replica denied any fault of this, saying that his powers had not grown enough, which resulted in her bashing him into the wall calling him "nothing but a mere toy". The Organization members later change their plans, hoping to turn Sora into their puppet and overthrow the Organization. Larxene suggested that Riku Replica's memories should be rewritten to be the same as the original's so he would become a much stronger and more useful tool.
Riku Replica, upon hearing Larxene's idea, rejected it, saying that he did not need his original's pitiful memories, but all the members began to agree upon Larxene's plan. Fearing that he would lose his memory, Riku Replica assaulted Larxene. However, he was quickly knocked out and Naminé was ordered to rewrite the replica's memory.
After having his memory rewritten, Riku Replica swore to protect Naminé, and saw Sora as a threat, feeling already betrayed by him as he thought Sora didn't care for him and cared only for Kairi. Sora's first encounter with the replica confused the Keyblade master. Sora managed to defeat the replica, who then escaped. Riku Replica later encountered Sora in Castle Oblivion's 8th floor, where he urged Sora to leave, as he would protect Naminé. Hoping to regain his friend, Sora offered to jog Riku Replica's memory, but nothing worked, and a fight ensued.
Riku Replica, defeated, felt even more anger when Sora offered his help so they could protect Naminé together. Hearing Sora say "together", Riku Replica is filled with sadness and rage and he screams his true feelings at Sora, telling him that he was always trying to worm his way into his heart and that it never mattered to him how he felt. After that, Riku Replica runs away, leaving Sora behind, confused.
Riku Replica's third encounter with Sora happens on the 11th floor, after his creator's demise, where he means to force Sora to leave. Sora, who has defeated Vexen, tells his friend that he is free, but the Riku Replica claimed that he was protecting Naminé from him, of his own free will. Riku Replica then tells Sora of the very same promise Sora made to Naminé when they were young. Sora claims that he was the one who made the promise and shows Riku Replica the lucky charm Naminé gave him as proof. In a rage, Riku Replica lashes out at Sora, and tells him that the Keyblade master's lucky charm was a fake, and the lucky charm he holds is the real thing. Sora and the replica fought, but the Riku Replica was once again defeated, and ran away.
Riku Replica's false memories come to an end on the 12th floor of Castle Oblivion. Meeting again with Sora, he insisted that he was the one destined to protect Naminé but Sora's wrecked memories kept interfering. Sora defeated the replica again, however, and when Sora went to help him, the Replica retaliated, knocking Sora back.
Just as Riku Replica was about to deliver the coup de grâce, a desperate Naminé shatters Riku Replica's false memories and his heart with them. Larxene later interferes, and explains Riku Replica's nature and creation (note that until this was revealed, Sora believed the Riku Replica to be "the real Riku"). An angered Sora fought with the Organization member, successfully defeating her. Riku Replica was last seen in the top floor of Castle Oblivion, where he saved Naminé from Marluxia. Despite losing his memory, he remembered his oath to protect Naminé. He protected her throughout the battle between Sora and Marluxia. In the end, he leaves Sora and Naminé, saying a fake like him does not deserve to be together with them; Sora, however, comforts the replica. Feeling Sora's warm kindness, the replica smiles and leaves. He still has one more thing to do: defeat the real Riku.
After leaving Sora, Riku Replica joined Axel, who would use him for enacting his (and Saïx's) own plans. They seek out the wounded Zexion, who is initially shocked to see them, believing Axel to be accompanied by "the real Riku". His relief does not last long, however, after Axel presents the replica with an idea, telling that if he gains power that the real Riku doesn't have, he could be something real, not someone's counterpart. Agreeing, Riku Replica approaches Zexion, and drains the life force out of him (initially giving him Zexion's powers). Riku Replica was later seen in a memory version of Twilight Town, where he meets Riku in front of the old mansion. The replica remarks that Riku no longer feared the Darkness, in which he earns the original's confusion in return. Riku Replica replies that he is Riku, and thus he would know everything about his counterpart. Feeling annoyed, Riku remarks that he is himself, and no one could possibly be him. Angered because of the fact that he is "a fake", the Riku Replica taps his Dark powers, and states that in the end, he was still nothing but a replica, even after gaining new power.
Blinded by jealousy and rage, Riku Replica engaged the original, and the two had a fierce battle. In the end, despite Riku Replica's new found powers, he was defeated, and slowly faded back into the Darkness. With his dying breath, he asks Riku where a replica's heart like his would go. Riku comforts the replica, stating that it would go to the same place as his. The replica smiles, and remarks "A faithful replica until the very end. That's... okay," before fading back into the Darkness.
Kingdom Hearts 358/2 Days[]
Riku Replica is mentioned once when Xion is revealed as a replica and is also mentioned in the Replica Program as "a numberless replica". Axel mentions Riku Replica in his own Secret Reports, stating that he is the only one who understands that Riku Replica gained a sense of self. He also expresses regret at having used the Replica as a tool.
Kingdom Hearts II[]
Although he does not appear in person, the Riku Replica is depicted in one of Naminé's drawings in the White Room.
On Sora's Team[]
When Naminé joined the team, Riku Replica joined to protect her from new enemies.