Repliku knows that he is a clone of Riku, and doesn't like the fact that his skill set is inferior to that of his template. In a way, one could say he is envious of his template because while Riku can wield a key blade, Repliku can't. It's somewhat of a sore point for him that he is not as good as the one he was based on. In addition, he doesn't understand why the key blade chose Riku or Sora, or how the process of choosing of such a blade actually works. Repliku wants friends of his own so he can see if they are the source of power that the key blade draws from, but isn't sure how to go about making friends, given that he was used to being under the control of others. As he was made simply to test Riku by Vexen, he is a little obsessed with not being compared to or being seen similarly to the original. 

Repliku also hates Vexen and by extension the other members of the Organization because he believes they were responsible for his demise. Repliku doesn't like it that he's forced into the battle by the deity of neutrality, but values the new lease on life he has been given. He's hell-bent on proving himself to be more than the sum of his parts, and that he is more than just a clone. In addition he has a score to settle with Vexen for what Vexen did to Xion, and how Xion was treated. It's somewhat of another sore spot of his, which is why he loathes the very existence of members of the Organization, except for Xion, Roxas or Axel. 

He's not sure how he feels about those three, but he doesn't hate them nearly as much as the members of the Organization other than them. In addition he is not sure how he feels about Riku, Sora, Kairi, or Namine. At one time he did feel love for Namine, but now he is not entirely sure how to feel about her to be honest. Repliku also longs for a new name for himself, a name that could make him more than a clone of Riku, even if he believes himself unworthy of such as he is a pathetic copy of the original, and can't match the original in combat. 

Created by Vexen because he took an interest in the original Riku, Repliku was intended as nothing more than a clone of the original. Defeated by Sora shortly afterward and having its heart destroyed by Namine, the Replica was able to revive but felt empty inside. Eventually, it was convinced by Axel to hunt down Zexion and acquire his power so that he could face Riku with power that Riku didn't have. Unfortunately,  said power was not enough and he ended up losing against Riku.  

Due to the battle's toll on him, Repliku died then and there but was told by Riku that his heart would go wherever Riku's was when he died. At peace, Repliku thought himself to be dead, but would later encounter Riku again. Instead of attacking him, however, Repliku left immediately. 

Repliku expired shortly after that, only to end up revived by the Neural Deity. While he doesn't like being forced to fight for the benefit of others, he does value his new lease on life. It is one of the reasons that he has chosen to stick to this path, while he attempts to prove himself more than a clone of Riku.