I actually have my own theory regarding this.
First of all, let me say that I'm a strong supporter of Ven=Roxas. Now, here's how it goes:
Nomura has been quoted in interviews as saying 1. Ven as well as Sora is Roxas's true self and 2. That Roxas takes a lot of himself from Ven. Therefore, it has been confirmed that Roxas is both Sora and Ven at the same time. However, since Sora is still around (thanks to Kairi), the one he takes from instead is Ven, helped by the fact that he has Ven's heart.
It's a fact that at the end of KHII, Roxas hasn't completely disappeared. And you have to wonder, why? Shouldn't he resonably have, given that he's back with his Somebody? Oh, and before you drag Namine into this, I believe there's a whole 'nother thing going on with her. There's even speculation that she might not even be a Nobody at all. Hell, we don't even completely know why she went into Kairi instead of Sora. So let's not get into that, 'k?
So why didn't Roxas disappear? Simple. Because he wasn't completely himself yet. Sora was part of him, but not completely. He gave the part of him that was Sora back when he fused with him, which included half of Sora's power. But he couldn't vanish, because there was another part he needed to give back. That remainder of him was Ventus.
I think when Ventus finally wakes up, 'Roxas' as we know him will disappear. This will be because 'Roxas' will have finally given back the remainder of himself to Ven, and completely disappear. However, I sincerly believe that Ven will inherit the feelings Roxas developed (he had Ven's heart after all) and possibly some or all of his memories. Therefore, Ven would have been 'Roxas' all along.
In other words, physically (in that he was able to wield the Keyblade, had half of Sora's power ect.) Roxas was Sora. I won't deny he was probably influenced slightly by that in other ways too (As indicated during the battle between Riku and Roxas). But mentally, he is MUCH more closely associated with Ventus. In that way, Ven is more Roxas's true self then Sora is.
Oh, and before you mention personality: Ven as we knew him had a heart of pure light. We never knew what he was like with darkness in his heart. For all we know, Roxas was pretty close to what Ven was like before MX messed with his heart. As for Ven's memories, remember when Roxas fainted in CO? He said that he saw images right before passing out. Although its implied that those images had to do with Sora, its not outright stated. So, I like to believe that Roxas had Ven's memories flashing through him, as well as images connected to Sora (No wonder he passed out, Ven went through a lot of crud and seeing even some of that again would be overwhelming).
First of all, let me say that I'm a strong supporter of Ven=Roxas. Now, here's how it goes:
Nomura has been quoted in interviews as saying 1. Ven as well as Sora is Roxas's true self and 2. That Roxas takes a lot of himself from Ven. Therefore, it has been confirmed that Roxas is both Sora and Ven at the same time. However, since Sora is still around (thanks to Kairi), the one he takes from instead is Ven, helped by the fact that he has Ven's heart.
It's a fact that at the end of KHII, Roxas hasn't completely disappeared. And you have to wonder, why? Shouldn't he resonably have, given that he's back with his Somebody? Oh, and before you drag Namine into this, I believe there's a whole 'nother thing going on with her. There's even speculation that she might not even be a Nobody at all. Hell, we don't even completely know why she went into Kairi instead of Sora. So let's not get into that, 'k?
So why didn't Roxas disappear? Simple. Because he wasn't completely himself yet. Sora was part of him, but not completely. He gave the part of him that was Sora back when he fused with him, which included half of Sora's power. But he couldn't vanish, because there was another part he needed to give back. That remainder of him was Ventus.
I think when Ventus finally wakes up, 'Roxas' as we know him will disappear. This will be because 'Roxas' will have finally given back the remainder of himself to Ven, and completely disappear. However, I sincerly believe that Ven will inherit the feelings Roxas developed (he had Ven's heart after all) and possibly some or all of his memories. Therefore, Ven would have been 'Roxas' all along.
In other words, physically (in that he was able to wield the Keyblade, had half of Sora's power ect.) Roxas was Sora. I won't deny he was probably influenced slightly by that in other ways too (As indicated during the battle between Riku and Roxas). But mentally, he is MUCH more closely associated with Ventus. In that way, Ven is more Roxas's true self then Sora is.
Oh, and before you mention personality: Ven as we knew him had a heart of pure light. We never knew what he was like with darkness in his heart. For all we know, Roxas was pretty close to what Ven was like before MX messed with his heart. As for Ven's memories, remember when Roxas fainted in CO? He said that he saw images right before passing out. Although its implied that those images had to do with Sora, its not outright stated. So, I like to believe that Roxas had Ven's memories flashing through him, as well as images connected to Sora (No wonder he passed out, Ven went through a lot of crud and seeing even some of that again would be overwhelming).