LOL. BlackOsprey and Master Spockanort, I'm glad that you like the AUs! I know they were a real joy for me when I found them
Not to turn this into an Arche Twist thread, but I just love the idea of it so much.
For one thing, Kairi being the hero is just so refreshing (Girl Power!), but also kind of fitting because she and Sora are very similar. But more than that, even though Kairi's supposed to be special as heck, she usually isn't treated as such in canon (that is, they never really do anything with her PoH or Keyblade wielders status), so she (sadly) kind of fits the dull, ordinary boy that Sora's supposed to be in that light.
Sora as Riku is also interesting. Because the creator of Arche Twist (in answering an ask) once said that part of the reason Sora doesn't trust Kairi in it (and why he's not working with her to save Riku), is because Maleficent puts doubts in his head like, "She really isn't interested in helping Riku. Remember when she wanted to go on the raft just with you, and leave Riku behind?" Which, honestly... really helps this AU along, because otherwise Sora probably would just work with Kairi to get Riku back. LOL. But it's such an interesting evolution of that scene, and I love it!
And Riku being a Prince of Heart is just the greatest thing ever to me (and the fact that, unlike Kairi in canon, he actually gets to go with the hero on some adventures and be involved with things). I just can't get over how someone who's supposed to have a heart of pure light would be as witty, snarky, and insulting as Riku is. But then Kairi sort of manages that, too, without it bringing any darkness into her heart. So Riku should probably be a similar same case.
And Riku was so the damsel in Coded. You can't even tell me that he wasn't.
And the fact that all the characters have their same personalities (and everything up to Night of Fate is still canon) just makes this all the more interesting, imo!
All the characters get to bond because of this! We get a ton of Sora/Kairi stuff, like we do with Sora and Riku in canon. We get some nice Riku/Kairi moments, and actually more of them than SoKai in the games (because Riku is adventuring with Kairi during Castle Oblivion and KHII). And we have our Sora/Riku (Riku/Kairi equivalent) instances, too: As Dakt said that one of the things they bond over is that they both think they messed everything up: Sora thinks he did for falling to darkness, and Riku thinks he did for opening the Island's door (because he still totally does that in this, being curious and all, but instead of teaming up with Ansem he gets Kairi-ified and loses his heart inside Kairi). LOL.
And of course the other switches are fun, too!
...I'm going to shut up now.