Soriku

Soriku is the slash ship between Sora and Riku from the Kingdom Hearts fandom.

Canon
Kingdom Hearts

Sora and Riku have been best friends since very early in the childhood. They had a friendly rivalry and always sparred together with their wooden swords yet they still had a great admiration for each other. Sora and Riku both shared the desire to travel to other worlds and this especially became the case after Kairi arrived. They decided to build a raft together but were eventually sucked away from Destiny Islands by the darkness.

As soon as Sora and Riku ended up in separate worlds, they wanted to find each other. They eventually ran into each in Traverse Town. Sora was happy to see him but Donald said that Riku could not join them so he ran away. Maleficent tried to convince Riku that Sora did not care about him anymore and seeing Sora smile with new friends made Riku angry, sad and lonely, so in that moment of weakness, on his moment where he thought Sora didn't care about him, Maleficent could easily manipulate him.. Riku began to side with the heartless which angered Sora. They fought multiple times in Hollow Bastion and Riku temporarily stole Sora's Keyblade until he overpowered his heart and got it back.

Riku was upset that Sora's heart overpowered his and allowed Ansem to possess him. Sora eventually figured this out and demanded that he gave Riku his heart back. While the closing the Door to Darkness, they saw each other again. Riku helped him close the door and told him to take care of Kairi. Sora decided to continue to look for Riku.

Kingdom Hearts Chain of Memories

Sora goes to Castle Oblivion and thought that he found him but it turned out that it was just a replica of Riku. Repliku was meant to show Riku's true emotions, what Riku couldn't express (How Sora abandoned them, etc.), so during the game and light novel, there are many scenes where he states that Sora always wormed his way into his heart, how he wants Sora to give him attention and such.

Kingdom Hearts 358/2 Days

Sora was eventually put into a coma as a result of having his memories tampered with. Riku was determined to help him wake up and learned about his nobody Roxas. He fought Roxas in an attempt to capture him but could not win. Riku decided to give into the darkness in order to win which transformed his appearance into Xehanort's heartless and temporarily caused his memories to fade. He watched over Roxas until he returned himself to Sora.

Kingdom Hearts II On the mountains in the Land of the Dragons, Sora meets up with a mysterious hooded figure who shows his keyblade to him, and cues to fighting a swarm of heartless. Sora, afterward, reaches out and softly calls his lost friend's name, hoping it was him under the hood. Meeting with everyone in the Imperial Square, he asks the emperor if the hooded figure said anything and smiles at Shang's answer, realizing he's the man he met in the mountains.

Since Riku had given in to the darkness and changed his appearance, he did not want Sora to find him. While Sora was traveling, he dropped him some clues in order to help him move on. Sora and Riku eventually found each other in the World that Never Was and had a heart-warming reunion, expressing how greatly glad he was that his friend is here and how he thought he lost him. After Riku's true appearance returned, Sora was the first to make him laugh after he questions if he'll be seen as the person he is.

Thinking they'd go home, the portal closing with everyone inside and eventually being the last ones there and defeated Xemnas together. Sora and Riku were trapped in the Realm of Darkness together and had a heart-to-heart conversation. Riku admitted that he had always been jealous of Sora but the best thing about him was having him for a friend. The Door to Light eventually opened and they returned to the Destiny Islands together.

Kingdom Hearts Dream Drop Distance

Sora and Riku spent some time at home until they received a letter from King Mickey. They were both called to take the Mark of Mastery exam by Master Yen Sid. They both traveled through the Realm of Sleep and with all the obstacles, they were determined to find each other and their actions still affected each other. In the Symphony of Sorcery world, Mickey states that their hearts were in tune, making them free to sing and created a powerful harmony while their "Sound Ideas" being Dearly Beloved, the main theme of Kingdom Hearts.

It was eventually revealed that Xehanort intended to use Sora as a vessel and Riku goes to save him. Meanwhile on Riku's fight with Ansem, it is revealed that Riku has spent the entire exam traveling through Sora's dreams as his Dream Eater. Returning to the Mysterious Tower, Riku enters Sora's dreams once again and releases his heart from a nightmare-possessed armor, saving him. He then lands into Destiny Islands which then he meets Roxas, Ventus, and Xion, answering questions (answers imply he wants to recover Sora) and Ansem the Wise who gives him data from Sora's heart. Afterwards Sora wakes up, his eyes lighting up once he hears Riku and shouts that he's safe, hugging him tightly twice as Riku asks if he's ok who then dismisses his concern. Sora states how he heard Riku the whole time. Right after their reunion, Yen Sid names Riku a Keyblade master and Sora showing excited towards his friend's achievement. 

Kingdom Hearts III

As Riku and Mickey go on their journey to find Aqua in the Dark World, Riku expresses how he's been into the realm of darkness before, knowing the place and says how it "seems like another life." Right after Mickey states how Riku grew over time, Riku replies how scared he was the first time and expresses that his fears and doubts are long gone, feeling exhilarated. Riku guesses that the feeling is maybe because Mickey's with him this time, which Mickey declines saying how he found that special strength to "protect what matters" and that "sometimes you care so much for somebody that others feeling disappears."

During Sora's journey in Arendelle, he meets Anna, who they find out is Elsa's sister. Questioning about what's going on, Anna shares her story on how close she was with Elsa and suddenly being shut out from her without explanation, but still determined to bring her home. Sora states that Elsa knows how much she loves Anna, with a sad expression he looks back on his friend that had also did what he could to keep himself away from him as he believed that it was for his own protection.

When Sora arrives in San Fransokyo, he excitedly says how he wants to show Riku "what a blast this place is."

In the Gummi Ship, Sora, Donald, and Goofy gets a call from Chip and Dale in worrisome that they lost contact with Riku and Mickey, alone in the Realm of Darkness. Sora expresses in anger how he should've gone with them. After Sora unlocks the door with Master's Defender in Destiny Islands and Riku's fight with Anti-Aqua, which exhausts him, breathes out his name and goes with Sora dropping down to him, a face of shock from Riku. Now together again, they both summon their Combined Keyblade and use it for the heartless tower that's keeping Mickey trapped.

Once Mickey was freed from the tower, Riku runs towards the injured Keyblade Master, which catches Anti-Aqua's attention to the teen, and she quickly raises her keyblade and rushes towards Riku, preparing to strike him down until Sora rapidly blocks her powerful blow, protecting Riku from harm. Sora tells Riku to tend to Mickey, and that he will deal with Anti-Aqua. Sora goes on to defeat Anti-Aqua, purging the darkness from her, and returning her to the realm of light.

At the day of the Keyblade Graveyard with everyone gone from the heartless tornado, Riku was the last one to not be taken away. Once Sora expresses how he's worthless without everyone else, Riku states how he doesn't believe that ("I believe in you. You will not give up." JPN) and with no fears, he walks away and fends off the heartless for a few moments with Sora behind him reaching out for his best friend until both being taken away. This can be seen as an act of true love as Riku continues to put his life on the line for Sora. After his encounter with Chirithy and the Final World, he comes back to Riku, again, walking off and this time waking up in a dark tunnel. Sora reaches out to the light, calling Riku for him to answer which then sends him to Olympus, finding him on top of a pedestal.

Once everyone closes Kingdom Hearts and returns to the Keyblade Graveyard, Sora says how he can't go home without Kairi. Mickey being concerned, not wanting Sora to abuse his power, Riku steps in telling him to let Sora go and that his mind and his heart is made up and to believe in him. In the secret ending, Sora and Riku are shown in a unknown world, separated from each other once again.

Kingdom Hearts III Re:Mind (Limitcut Episode)

After a year from Sora's disappearance, Riku goes to Radiant Garden and meets up with the Radiant Garden Restoration Committee. He tells them how the Guardians of Light have spent the year searching for Sora, but no clues were found. With Cid having to recreate Sora's data battles with Organization XIII, Riku then challenges the data battles in hopes for any answers about Sora.

Once every data battle has been completed, a screen on the computer shows that Sora's data hasn't been updated, landing everyone down to square one again. Suddenly, Fairy Godmother appears, to aid them at Merlin and Yen Sid's request and asks of Riku's presence. She asks Riku about the dream he's been having, the teen replied that he was surrounded by tall buildings looking for Sora with someone watching him from afar. Fairy Godmother states how Riku was in Sora's dreams before and that Yen Sid and Merlin believe that Riku might be the key to having clues on Sora's whereabouts, including two others. 

Fanon
Soriku is a rather popular Kingdom Hearts ship, possibly the most popular among Riku's ships. The ship especially became very popular after Kingdom Hearts II and grew stronger from Dream Drop Distance. This was the first game where there were no ill feelings between the two and their relationship was emphasized more. Many fans feel that there is no way that the two are just friends, and some like to speculate that Riku could be a love interest for Sora, at the very least a one-sided one.

Fandom
FAN FICTION
 * Riku/Sora tag on FanFiction.net
 * Riku/Sora tag on FanFiction.net

Trivia
"At that moment, I didn't even realize what was happening around me. I didn't even look. Sora, at the end of my outstretched hand, was so much more important than everything else."
 * In the Chain of Memories Light Novel, as well as the 358/2 Days novel, we get to see insight on Riku's take on the story, which hints that he may harbor more than friendship feelings for Sora.

"I wonder if I really will meet someone from my memories in this castle. I want to meet Sora, more than Kairi. More than anything, I want to see Sora. I want to see him-- and apologize."
 * In the Days novel, he thinks of Sora in order to regain his will to fight "Everything's for Sora", to the point he sacrifices his own body to the Darkness, if that meant Sora would wake up.
 * Sora doesn't fall too behind, as during the novels, his thoughts were on Riku only. Plus, this one line from the KH2 Novel, after their reunion.

"How hard did I look?

How hard did I miss him?

How much did I think, I want to talk to him again?

Riku is... here. I finally got to see him again, I missed him.

I missed him so, so much."
 * In the KINGDOM HEARTS Episode IV: Chapter of Dawn, it's stated that Riku fought to get his precious thing (person) back, which is implied to be Sora.
 * In KH2 novel, it is confirmed that Sora starts crying once he saw Mulan and Shang together, thinking about Riku.

"As Sora looked at them together, he noticed his vision growing blurry.   “Sora…?” Goofy set a hand on his shoulder.   Donald peered into his face.  “Crying for joy?”  “I’m not crying!” Sora turned away and scrubbed at his eyes.  He was not.   There was no reason to cry when he was glad.  Riku was alive.  I want to see him.  I have so much to tell him.

Riku…!"
 * In an Interview with Nomura, he said that Passion was themed after Sora and Riku's reunion, the song, its English counterpart, Sanctuary, show a long of romantic hints.
 * " Following the previous game, Utada Hikaru also sang the theme song for this game, "Passion."  Nomura:  Many fans seem to have the image Kingdom Hearts = Utada Hikaru so I didn't think of changing that at all. This time I wrote a story explanation for her that's longer than the previous game's. We decided to have it played at the last scene, so for me the theme was "Sora and Riku's reunion." I wrote stuff like "An image of a reunion, a happy moment in a way" and "Like a Hikari 2" in there." - Via KHInsider
 * In an interview with Shinji Hashimoto, he states “The fact is that the main focus of the series is Sora and Riku; how their friendship develops, but also how they grow up,” he says. “After so many years, the players’ personal growth is closely tied to the game’s story at this point, so that’s the most important thing about the series and what we want to put into the game.” - Via IGN
 * In Kingdom Hearts Dream Drop Distance and Kingdom Hearts III, Sora and Riku both share Nightmare's End and Mirage Split, which becomes the Combined Keyblade which wears a Paopu Fruit keychain. This could imply their destinies are intertwined, despite not actually sharing it.
 * During the tutorial section of Kingdom Hearts III, a re imagine of Sora reaching a light mirrors the Kingdom Hearts opening of Sora reaching out to Riku. Some fans theorize that the light is Riku that is still out of reach from him.
 * In the new loading screens for the Limitcut Episode in Kingdom Hearts III Re:Mind, Riku's post repeats his quote from the Keyblade Graveyard before Sora leaves to get Kairi back. His hashtag contains #wish which can connected to Cinderella's A Dream is A Wish Your Heart Makes and Fairy Godmother's appearance about his dreams.

Variations

 * SoRiKai refers to the ship between Sora, Riku and Kairi