Riku Replica

Riku Replica is a direct copy of Riku who appeared in Kingdom Hearts: Chain of Memories. Riku Replica, as his name implies, was created via Sora's childhood friend, Riku's combat data. Originally a subject to test out Riku, Riku Replica was later exploited to become a puppet of Marluxia, attempting to use Riku Replica to manipulate Sora and overthrow the Organization.

Creation and purpose
The Riku Replica was created by Vexen in a battle 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 beaten down by the original. Riku then attempted to destroy the Replica, but failed when the Riku Replica utilized the power of Darkness.

Sora's storyline
Riku Replica escapes, and eventually ends up in the Organization's head floor, Larxene taunted Riku Replica over his loss, however, the replica denied any fault of his, saying that his powers had not grown enough. 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; 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. 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. Filled with rage and jealousy, Riku Replica screamed his true feelings at Sora, and ran away in a fit.

Riku Replica's third encounter with Sora happened on the 12th floor, where he means to force Sora to leave. Sora, who has defeated Vexen, tells his friend that he is free. In a rage, Riku Replica lashes out at Sora, and tells 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 comes 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, when Sora went to help him, the replica retaliated, knocking Sora back, just as Riku Replica was about to 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 real thing.), 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 Namine from Marluxia, despite losing his memory, he remembered his oath to protect Naminé. He protected Naminé throughout the battle between Sora and Marluxia. In the end, he leaves Sora and co. saying a fake like him does not deserves to be together with them,Sora however, comforts the replica. Feeling Sora's warm kindness, the replica smiles and leaves. But he still has one more thing to do. Defeat the real Riku.

CoM manga
Riku's replica never fights the real Riku. However, he encounters Riku, and tries to make himself look taller. When Riku blatantly ignores him, the Replica visits Vexen's grave, where he encounters Vexen clones, who keep following him. He also takes a bit off a piece of a rice cake, and puts a chain on it, pretending that it's a "new good luck charm." Referring to Naminé giving him the fake luck charm.

Also, the Replica only fights Sora once. The second time he is encountered by Sora, he simply grabs Sora's good luck charm and attempts to smash it before Naminé kills him.

Reverse Rebirth
After leaving Sora, he joined Axel, a member of the Organization, they seek out the wounded Zexion, who was shocked to see Riku, but was relieved to know that the "Riku" he saw was just the Replica. 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 lifeforce out of him. Riku Replica was later seen in a memory stimulated Twilight Town, where he meets the real 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, Riku taps his Dark powers, and states that in the end, he was still a replica, even after gaining new power, he was still nothing more than a replica. Blinded by jealousy and rage, Riku Replica engaged the original, and the two had a fierce battle. In the end, despite Riku Replica's newfound 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 "How original." before fading back into the Darkness.

In Combat
The Riku Replica fights with the same style as the real Riku, but his sleights take less power than Riku's. For example, Riku can only use Dark Aura with three 9's, a total of 27. However, the Replica can use any three cards, such as 4, 7, and 8 to perform Dark Aura. He is also more aggressive, which leads to some open moments during his battles.

Card
See: Riku Replica (Enemy Card)

Personality
The Replica was more aggressive and protective than Riku, which is exactly what Xehanort's Heartless was looking for. He was also more stubborn, made him more of an enemy in the game. At the end of his life, the Replica became much more like the original, becoming sullen and mellow. He was quick to anger, and 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 under Ansem's Possession.