In the cutscene where Sora gains most of Roxas' memories, I've been thinking recently. Is that just an illusion of Sora's dreams, or is that Roxas' consciousness?

 

I said most of his memories, because of what happened in 358/2 Days.

I think it's a bit of both. Like Ansem said to Riku, "Dreams hold our memories". Sora has so many memories that don't belong to him, I think being sent into such a deep sleep affected Roxas and brought those memories to the surface, Ven's, Roxas' Maybe even Xions. This is the "hurt" Data-Namine warned Data-Sora about and Xehanort took full advantage of it.

Edited August 14, 201510 yr by Isamu_Kuno

Personally, I think that this is all in Sora's dream, since he is in the Dream World, and well, Roxas appearing before Sora is all part of the dream!  It's kind of like when we have dreams!  Sometimes, while dreaming, we remember things we had thought were long forgotten, as is the case with Roxas.

That was actually his memories. Remember what Xigbar said "The falling asleep part was definitely our bad, but we can't go putting stuff in your head." How much truth is in that statement has yet to be seen (considering how it's Xigbar talking, of all people), but it is a reasonable explanation in terms of logic. They can't control the content of what Sora sees in his dreams, nobody can, not directly. It is likely that they can probably influence what Sora sees however, as most dreams are made up of what's already in your head. So since all of that pain from all of those people are already within Sora due to those connections, the Nightmare (as in the Anti-Black Coat) is likely provoking them to appear in front of Sora, being used as breadcrumbs to lure him deeper into his dreams. It's possible that it was taking memories that already existed within Sora and pulled them out and distorted them in order to lure Sora deeper in. The deeper the dream you are in, the more your dreams tend to dig out from your subconscious. Since Sora was forced into such a deep dream, a lot of the things from the deeper parts of his mind and heart start to surface as a result, Roxas being one of them. It's likely that a lot of this also stems from Sora's heart itself, as Sora never met Xion so there's no reason why he would have any idea what she would look like in his mind. It's his heart that is aware of all these people, not his mind. And as Roxas is a person who actually exists within Sora and Sora actually recognises this he is actually able to communicate with him...or he simply chooses too, it's a bit hard to say (what with him being all unnervingly neutral about the whole thing). With that in mind, it makes sense that Roxas is able to share his memories and feelings with Sora, since they are both within his mind in a sense, so it's probably easier to do that, unlike Sora just feeling what Roxas felt without understanding why in KH2.

Well Mr. Hero of Light XIV, now that you mention it. It does seem possible that Roxas might communicate with Sora whenever he wants. Not to mention that his memories did help Sora catch on to the fact that Nobodies can grow new hearts.

Well, doesn't Roxas shake his head when Sora asks if he's dreaming?

I think it's a bit of both. Like Ansem said to Riku, "Dreams hold our memories". Sora has so many memories that don't belong to him, I think being sent into such a deep sleep affected Roxas and brought those memories to the surface, Ven's, Roxas' Maybe even Xions. This is the "hurt" Data-Namine warned Data-Sora about and Xehanort took full advantage of it.

 

My question is, how does Xehanort know that Ventus' heart is resting in Soras?

Who says that Xehanort knows that? And that is off topic.