riku
Riku, the enemy and later hero of Kingdom Hearts. The one destinied to be chosen by the keyblade, but not chosen as he caved into the darkness. Down to earth, sincere, and keeping himself to himself, he found Sora's attitude to him after the destroyal of
Destiny Islands disheartening; as if he believed Sora had 'replaced' him and forgotten about Kairi. His errors were righted at the end, locking himself in the realm of darkness. In Kingdom Hearts 2, he suffers from his past, and rights the wrongs he committed to Sora and his friends, by taking on the darkness himself... and they became better friends. Enough about Riku, for now, and onto the Riku/Kairi relationship.
never mine
During Sora and Kairi's conversation, Riku appears. He then shares a few lines of speech with Kairi; stating that they do indeed know each other, though Riku shows slight annoyance towards her, though seems more overprotective than anything else. But their relationship is much deeper than being good friends. Riku, when he has a race with Sora, says that the winner gets to share a paopu fruit with Kairi. He claims he was just teasing; but this could mean he himself, had feelings for Kairi, or he was just doing it to wind Sora up. We'll never know. Either way, his entire idea of leaving the island came from Kairi's arrival; which he states.
After his short-lived reunion with Sora, he asks where Kairi is. One of the first things out of his mouth, actually. As Maleficent tells him, he has been replaced by Donald and Goofy; so Riku, alone, goes off in search of Kairi by himself. He does indeed find her, first, actually. Though, her heart is gone, and he wants nothing more than to return it. Even, to embrace the darkness, control the heartless, and work with Maleficent. Even though he turns into Ansem from being overloaded with darkness, his original reason.. was all for Kairi. He is concerned at Sora's lack of wanting to know where she is when he encounters him. He even recklessly goes to Hollow Bastion without use of a vessel with Kairi. That, takes a great deal out of him.
Either way, when he is completely consumed by Ansem, he even stands up to him, blocking his path, telling Kairi to run. Even though Sora is 'gone', so to speak, he still stands up and protects her, putting himself at risk. During the time when the door is closed between Sora and Riku, he speaks his last line in the first game to Sora: 'take care of her'. Her, meaning 'Kairi'. Having played the second game, there is significance behind this. Maybe, Riku believes Sora can indeed take care of Kairi and was just testing him before to see if he could. Maybe, because he knows he can't come back and he cares about her a lot, so tells his best friend to look out for her instead. Or maybe he does love her, but knows Sora loves her more than he does. Or something. There are many reasons with valid points.
As far as I am aware, nothing much changes in the relationship during the course of CoM, since Kairi never appears directly within the game. Either way, the second game. Kairi speaks of Riku fondly, as a friend would, to Selphie on Destiny Islands. Riku, under the guise of Xenahort's Heartless (Ansem) spends a lot; and I mean quite a lot; of time looking out for Kairi. When Kairi runs away from Axel, for example. Who is whistling? We never find out, but when Kairi is travelling through the inbetween, she sees a cloaked figure. If it was Axel, he would have got her. If it was another Organization member, they most likely would have done the same. So, is it Riku? My personal opinion is yes; that he is watching out for her. He's making sure she is ok, but is ashamed by his appearance so does not give himself away. As happens during the time Namine announces it is Riku; Kairi is surprised. Very surprised, in fact. She stops him from leaving when he attempts to, and even though she sees the face of Ansem in front of her, knows in her heart it is indeed Riku. She believes in him.
Riku presents Kairi with her keyblade (which is unnamed), and they fight together until Sora arrives. She even shows Sora that it is indeed Riku, and again, stops him from leaving. Throughout your climb of the castle, the pair are often shown standing together. The simple reason is as Sora's 'council' as they are, since they are his two best friends; I personaly see nothing more beyond that. Either way, throughout the battles when Riku remains as Ansem; he protects Kairi. When the group fight Saix, Kairi and Riku are blown out of the arena, but Riku protects Kairi in the process. The relationship is a lot more protective, now; sort of like the 'I've given up' vibe, to a certain degree.
For the remainder of the game, they are mainly seen as Sora's council and back-up. They don't paticularly share any more conversations with each other, though when Kairi vanishes into the portal and Sora and Riku are trapped, Riku uses his common sense and gets them out. During the talk on the beach before the ending sequence, he agrees with Sora about the realm of light being safe. One thing, is because Kairi is there. He believes in her, as she believed in him. It appears there is a lot of 'belief in each other' for their relationship.
The future, you ask? Well, unless Square make a very negative or suprise turn-around, these two will never end up as a romantic relationship pair. The protection, for Riku's side, and the belief in each other, for both sides, will more than likely reamin. For me, I see it progressing more so in the direction of the close 'brother-sister' relationship in the future.
like me and you
This is something you would imagine to see in a Sora/Riku shrine; but these are similar relationship pairings I have digged up. It's kinda easier for people to relate if you know them, afterall.Currently under immense thought (ie, she's not sure who is similar).