Technically they did though- in Country of the Musketeers with the whole stage trap thing that Riku negated and in Symphony of Sorcery where they both had to get separate Sound Ideas to play at the same time to save Mickey.
If one had faith in the writers, one could even say that it was intentional, to have the last two worlds before TWTNW show more interaction between the two to show how close they really were the whole time, and how deeper into dreams they were sinking.
Ok, that's more like it.
they didn't directly interact though. They influenced each other's world, which makes sense in an Inception sort of way. When they actually see each other they're intangible holograms though.
Something along those lines is likely, but it doesn't seem to be explicitly stated to my knowledge. I think another possibility could be that the dream Riku explores is the dream the new Org made to double trap Sora in the first place, meaning that it would be the physical Sora Riku is interacting with (which would explain why they CAN physically interact)
But yeah, like I said before, TWTNW kinda throws a lot of the established rules to the wind
As I said, I think it might be that while Sora is trapped in the nightmare world of TWTNW, Riku was still stuck in the Sora's dream of that dream. It's like layered cake almost, if the real world is the frosting and the layer underneath that is the dream that Sora is in, then the layer under that is the dream that Riku is in, and it becomes affected by Sora's layer and vice-versa. That being said, I'm not so sure that the Sora that Riku finds is the "real" Sora, but that rather it might be the metaphorical representation of the nexus of Sora's dreams, and that Riku is able to do things like grab him because he's a Dreameater and he's able to do interact with dreams like that. So when Sora falls into slumber, the nexus Sora disappears and the stability of the two-fold dream Riku is in starts to fall apart.
Yup, this is still fun.
Edited by Hero of Light XIV, 12 April 2015 - 01:41 PM.