THe other day i'd watched a video of the fight against the E.S. At the start, Sora and co enter the dark portal type thingy in the cornerstone hall. After they enter, they reach Sunset Horizon, The exact place where the secret ending took place. After a few seconds, there a minor sandstorm and the E.S appears in front of Sora kneeling. Now what I think is that the E.S had stayed and remianed at Sunset Horizon after the secret ending battle to find Ven adn Aqua. So basically he hasn't left Sunset Horizon since his last battle. He'd been searching everywhere for Ven and Aqua for years and made no proress. So what I think is that he'd opened up a portal waiting for Xehanort to appear. But instead of Xehanort, Sora had appeared. So everytime someone goes through that portal, he'd appear and check to see if it was Xehanort. Because obviously the E.S is waiting for Xehanort to appear.
Blizzard
Blizzard