I think that the reason Roxas is so special, is because he has Ven's Heart.
We all know (or at least assume) Roxas looks like Ven because Ven's heart rests within Sora's heart after it was damaged.
Assuming that when Sora released his heart and became a heartless, Ven's heart may of stayed with Roxas giving him feelings.
In order to save Ven, Roxas will have to merge with him, to fix his damaged heart.
In order to find Ven, Aqua must be freed from the realm of darkness.
And once they're both been sorted they can defeat Xehanort (once the heartless Xehanort, and nobody Xemnas have been destroyed the original being will be restored, that being Xehanort, as he was as a lab apprentice).
Sora, Ven, Aqua could then try to defeat/separate Terra from Master Xehanort.
Most people already know this but I just figured I'd put it out there anyhow http://kh13.com/forum/public/style_emoticons/default/happy.png
I think that the reason Roxas is so special, is because he has Ven's Heart.
We all know (or at least assume) Roxas looks like Ven because Ven's heart rests within Sora's heart after it was damaged.
Assuming that when Sora released his heart and became a heartless, Ven's heart may of stayed with Roxas giving him feelings.
In order to save Ven, Roxas will have to merge with him, to fix his damaged heart.
In order to find Ven, Aqua must be freed from the realm of darkness.
And once they're both been sorted they can defeat Xehanort (once the heartless Xehanort, and nobody Xemnas have been destroyed the original being will be restored, that being Xehanort, as he was as a lab apprentice).
Sora, Ven, Aqua could then try to defeat/separate Terra from Master Xehanort.