Demyx/anyone. He's an idiot, and he's ugly. I really don't see the attraction to pair him with anyone. Or to him, for that matter, but that's a different story.
Sora/Kairi is boring, like people have said before (Why is it that Kairi's the original and Namine's the nobody? Why does she have to go away? She's cool. Kairi isn't, and we're stuck with her.).
I see a lot of one-sided possibilities in the actual game (fanworld aside). It could be possible that Namine had a thing for Sora, even though she knows it's only because she rearranged his memories. Riku might have had a thing for Kairi in one point in time (they grew up together, it could have happened). Roxas might think Namine's cute in the five days that he gets to know her before becoming a part of Sora again. And there even might be a slim chance that Axel is gay (WHO cries when Roxas has to go back to Twilight town?), but Roxas would never notice--he'd probably be freaked out if he ever found out. But as far as actual two-way pairings go, I agree with most people in saying that it's pretty much Sora/Kairi or bust.
In the fanworld though...it's completely different. People's imaginations start running loose, and pretty soon you get a story about two organization members who, dropped into a fictional situation, actually work together. It's just in the game's parameters, it would never work.
Which is why I support shounen-ai pairings like Axel/Roxas and Riku/Sora, even though I know quite well that there's no chance of a snowball in hell that SE would put out anything official to that effect.
So I guess I support a bunch of pairings in the fanworld that I don't support in the actual parameters of the game. If that makes any sense...
My sister's friend had gotten KHII and was done with KHI, so she gave it to my sister. I started watching my sister play it, and liked it. I thought the idea of combining Disney and Squeenix (hehe) was cool. Finally, she was like, "Hey, why don't you start a game?"
The last thing I had played frequently was Harry Potter and the Chamber of secrets. For PC. With the arrow keys.
So, after watching the cool intro and being amazed by the graphics on the PSII (I'd seen it on youtube, but there's nothing like watching it on a TV screen), I start trying to figure out how to run, walk, etc. ("where's the O button?!!?!") My sister was rolling on the floor laughing as she watched me try to get sora to jump onto those little &^%$@%# palm trees when you're trying to race Riku at the beginning of KHI.
Needless to say, if Riku had kept his word, he and Kairi could have eaten all the Papou fruits on the island before I crossed the finish line.
Then when my sister's friend got done beating KHII about three times in a row, she lent it to my sister, and my sister had to explain to me how the hell sora ended up floating in a bubble. Which was funny, because she was reiterating what she had read offline from summaries of CoM, and she didn't exactly go in chronological order. I REALLY got lost when she tried to explain the nobodies concept.
Still, the game was amazing, and here I am, making music videos, and eagerly awaiting KHIII, hoping someday I'll be able to play KHI and II final mix, and Re:CoM.
Between the crossover factor, new disney movies, new final fantasy characters, AND the fact that they keep on letting out little hints about a LOT of the characters already there that they could easily give a ton more background/history on, I'd be surprised if Kingdom Hearts DIDN'T turn into the next final fantasy--especially with an organization of thirteen nobodies, only one of whose 'somebody' you actually know about. And what if they decide to go back in time, and fill in gaps, or follow up on other people? What if they keep going back further to what was happening in the other worlds when Sora, Kairi, and Riku were two?
And what about in between? all of THAT?
the list goes on.
there is more than enough plotline and potential to work with.