The plot gets even more complicated!
Holy shit, how is that even possible?! Apparently by stabbing himself in the chest and releasing all those hearts, Sora creates Nobodies for both himself and Kairi before turning into a heartless. Kairi doesn't like that much though, and uses magic princess powers she didn't know she had (insert groans here) to give Heartless Sora his body back. The Sora and Kairi Nobodies still exist, but are now 'incomplete' and/or 'ballsed-up' versions of what they once were.
Those two incomplete Nobodies became Roxas and Namine, who had Sora's Keyblade powers and inexplicable memory-warping magic respectively. Those are both really useful skills, so Organization XIII scooped them up to help out with Xemnas' own diabolical plans. Fun fact: it seriously took me years to parse all that nonsense. Goddamn.
Explained in: Kingdom Hearts, Kingdom Hearts: Chain of Memories, Kingdom Hearts 2
Riku doesn't know how doors work and Sora saves the galaxy
Meanwhile, Sora is blissfully unaware of all of this and is doing his own thing. After recovering from being Disney-dead, he abandons Kairi for her own safety (yeah, get ready for a lot more of that) and chases the possessed Riku to the end of the world. No for real, the final stage is called End of the World, and it's really, really weird. There, Sora and pals find and confront Not-Riku, at which point Ansem reveals his true form (Sephiroth plus Fabio divided by orange contact lenses) and then transforms into the universe's most terrifying cruise ship. A smackdown ensues and after Ansem gets the boat beaten out of him, he opens the door to Kingdom Hearts and explodes.
Sora, Donald, and Goofy try to close the door because its chocked full of Heartless, but they can't do it alone. Thankfully Riku (now no longer evil and significantly better-dressed) and Mickey Mouse show up and valiantly sacrifice themselves, helping Sora close the door with them trapped inside. No explanation for why they couldn't just walk out and push from the other side, but whatever. With order apparently restored and the universe realigning, Sora says a tearful goodbye to Kairi (who is suddenly there for some reason), and is swallowed into the folds of the galaxy.
Explained in: Kingdom Hearts
Sora fights Organization XIII and becomes an amnesiac
Having no freaking clue what to do with this death-chasing band of crazy people, the universe spits Sora and friends out at Castle Oblivion, where Organization XIII is running the show. They've got a whole Heartless-killing operation going, sending Roxas (who looks exactly like Ventus, because this series loves mistaken identities) on missions to release more hearts alongside two other Nobodies named Axel and Xion. Still, two mindless slaves are better than one, and when Sora stumbles in Xemnas gets the bright idea to use Roxas and Sora, which means somehow taking over Sora's mind. The appointed head of Castle Oblivion, Marluxia, obliges, but only so he can use Sora to overthrow Xemnas and take his place. Sneaky, sneaky.
To pull that off, Marluxia uses his favorite tool Namine, who starts writing herself in place of Kairi in Sora's memories, making him susceptible to her influence. She feels bad about that though, like any decent not-human would, and when Sora fights Marluxia for her freedom she promises to set his memories right. But she has to load him up into this giant egg and put him to sleep for two years to do it. That's cool, right?
Explained in: Kingdom Hearts: Chain of Memories, Kingdom Hearts 358/2 Days
Riku kills his other self (but not the one he meant to), and Roxas is next
Sora takes the deal and goes under, but that's not the end of the shenanigans in Castle Oblivion! Remember Ansem the not-so-Wise from earlier? Well he's pissed and out for revenge (plus going by the name DiZ, for some reason), and decides to put his plan into action. Finding Riku in a nebulous darkness realm, he reveals that a piece of Heartless Ansem will always exist within the poor kid, but if he finds Namine, she can help him lock it away. So Riku heads on a journey of self-discovery (during which he finds and kills a Frankenstein version of himself created in a lab, which probably wasn't what he had in mind).
Along the way, he gains the nifty ability to change back and forth between Ansem and an older, blindfolded, emo version of himself. This comes in handy when he finds out about Soras coma and Namine tells him the only way for Riku to wake the dipshit up is to take out some dude named Roxas. Okay, now we're getting somewhere!
Explained in: Kingdom Hearts: Chain of Memories, Kingdom Hearts 358/2 Days
Things get weird with Xion and Roxas
So while all of that was going on, Roxas was developing a personality and spending 358 days eating sea salt ice cream with Axel and Xion (ooooh, now I get it). Remarkably, he doesnt gain any weight, but his non-heart is broken when Riku shows up and not only drops the bomb that Roxas is Sora's Nobody, but so is Xion. BECAUSE WHY NOT, RIGHT? HAHAHA, THIS ALL MAKES TOTAL SENSE!
After clarifying that Xion is a bi-product of the insanity caused by Kairi un-deading Sora, she has an identity crisis over being an expendable meatsack. She and Roxas bail on the Organization, which doesn't end well, as Riku catches up with them and Xion ends up merging with Roxas. At first, Roxas beats Riku, but then Riku turns into Ansem to knock Roxas out and seriously, is anyone really following this? Either way, Roxas is defeated, and Riku drags his sorry butt back to DiZ and Namine. I just I don't even
Explained in: Kingdom Hearts 358/2 Days
Roxas is the victim of a three-hour Matrix homage
DiZ and Namine plug Roxas into a computer Neo-style, dropping him in a fake version of Twilight Town full of fake friends during a fake summer vacation from fake school. Eventually, Roxas gets wise and confronts Namine, who tells him that theyre actually both Nobodies so they should totally hang out. Axel also pops in a couple of times, trying to remind Roxas that they were super good friends despite their inappropriate age difference, but Roxas knows better than to talk to strangers and breaks Axel's not-heart.
The digital Twilight Town weakens the longer Roxas pokes holes in it, and it eventually becomes completely unstable. DiZ disappears with Namine and Riku (who still calls himself Ansem), giving Roxas room to take the red pill and bust out of the simulation. Axel cuts him off at the pass and goes into if-I-can't-have-you mode, at which point Roxas kills him and they share a tearful goodbye (that's unbelievably confusing if you didn't play 358/2 Days first, which was released four years after KH2). After shaking the blood of fratricide off his Keyblade, Roxas finds Sora in his flower-egg cryo capsule, and disappears as all of his memories and personality revert to Sora.
Explained in: Kingdom Hearts 2
Sora wakes up, beats monsters, cries about Riku
After Sora wakes up, discovers he's hit puberty, and reunites with Donald and Goofy, they resume their search for hide-and-seek champions Mickey and Riku. This time around the galaxy, Organization XIII are the ones to beat, though Marluxia's coup d'etat has knocked their numbers down to half. Their dastardly plan to make Sora kill a bunch of heartless and force Kingdom Hearts to appear is revealed, and they kidnap Kairi just to piss Sora off. Namine helps break Kairi out and merges with her (err), just in time for Kairi to run into Ansem-Riku and force him to actually talk to Sora instead of being a big baby.
After the three share a tearful reunion (where the only one crying is Sora and it's kind of embarrassing), Mickey shows up in an Organization XIII coat, making the most badass entrance he has made in anything ever. DiZ shows up too, with some sort of machine to encode Kingdom Hearts as data, which he thinks will somehow fix everything. Why do they call this guy wise, again?
Explained in: Kingdom Hearts 2
Everything turns out okay
The machine does exactly what you'd expect: it explodes, blows up Kingdom Hearts, and leaves Sora and Riku to deal with Xemnas inside of a monochromatic painting. So damn predictable. Together they put the smackdown on Xemnas and destroy Castle Oblivion, which leaves them nowhere to go but that in-between world where Ansem and Aqua both ended up. Pretty steady population growth, there.
While the two don't seem all that upset about spending the rest of eternity locked in endless twilight together, a hallucination of Kairi is still kind enough to get them out. Through the POWAH OF FRIENDSHIP they wind up back on the island they first tried to escape, along with Goofy, Donald, Mickey Mouse, and Kairi.
Explained in: Kingdom Hearts 2
...for now
Okay, stick with me, we're almost there! After the secret ending of Kingdom Hearts 2 where it's revealed Sora left Destiny Islands to help King Mickey once more (because good is stupid), our Disney pals discover a long-forgotten note from Namine, which reads: "Their hurting will be mended when you return to end it." Eventually, they figure out that the note is revealing Sora's true purpose, which is to save everyone tied to his heart, including Roxas, Ventus, Axel, Xion, Terra, and Aqua. I kind of thought it was to save the whole galaxy but okay, I'm done asking questions.
Sora and Riku also go to meet with Mickey's old master, Yen Sid (i.e. the Fantasia guy), who instructs them to take the Keyblade master test so they can become true wielders and save the world from a new, encroaching evil. And by new I mean old, because apparently destroying both Ansem and Xemnas means Xehanort is going to come back fully formed, so the last four games meant literally nothing. FAN-FREAKING-TASTIC. But at the very, very end we find out that Yen Sid's also going to train Kairi to use the Keyblade, making her, Sora, and Riku a proper world-saving trio, so all is forgiven.
Explained in: Kingdom Hearts re:coded, Kingdom Hearts 3D: Dream Drop Distance
Is there's any more room left in your skull, check out 10 insanely complex video game plots explained (in 10 words).
