In order for anyone in KH to weild the light and the dark back to back I beleive that they must first engulf themselves willingly in the darkness at which time if they don't get 'eaten' for want of a better term, they can recover and use the dark after they have fully returned the light.
When Sora stabbed himself with the heart-unlocker, he realeased his heart and submerged himself in the darkness. When Kairi came brought him back he was completely bathed in the light since she is a PoH. In KH2 when we say hello to anti-form, we are proving that once you have entered the darkness of your own free will, your dark powers are able to reaturn whenever they wish if you haven't learn to control them.
For Riku we know what happened. He was taken into the darkness when he opened the worlds so that the three of them could get off the islands. He was only in the darkness at this point. When Ansem/Xehanort took him over, he becam completely engulfed because Xehanort was. During CoM he struggles to get out of the dark and into the light which is why at the end he goes on the road to dawn. During two he stays in the darkness until the very end and can no longer weild the dark. Just as we thought Sora couldn't. So most likely in three (if there is one) Riku will show signs of anti-fromness.
The point of this is really only in the first paragraph. The other two were examples of course. Now thoughts? Opinions? Anything...
When Sora stabbed himself with the heart-unlocker, he realeased his heart and submerged himself in the darkness. When Kairi came brought him back he was completely bathed in the light since she is a PoH. In KH2 when we say hello to anti-form, we are proving that once you have entered the darkness of your own free will, your dark powers are able to reaturn whenever they wish if you haven't learn to control them.
For Riku we know what happened. He was taken into the darkness when he opened the worlds so that the three of them could get off the islands. He was only in the darkness at this point. When Ansem/Xehanort took him over, he becam completely engulfed because Xehanort was. During CoM he struggles to get out of the dark and into the light which is why at the end he goes on the road to dawn. During two he stays in the darkness until the very end and can no longer weild the dark. Just as we thought Sora couldn't. So most likely in three (if there is one) Riku will show signs of anti-fromness.
The point of this is really only in the first paragraph. The other two were examples of course. Now thoughts? Opinions? Anything...