Personally, I think many people are believing that the MF is related to Xehanort/Xemnas. I think differently. Ven lost his heart, so wouldn't that give him a nobody? I believe that the MF is Ven's nobody. He holds the "Ethereal Blades" backwards, and c'mon, how many characters in the Kingdom Hearts storyline hold their weapons backward? As for the reason why Ven would be fighting his own nobody...well, Aqua supposed to be in the realm of darkness, Terra is possesed by Xehanort, and Ven lost his hearts (therefore creating the MF). Therefore, the fight against the MF has the same concept as the secret ending; everybody said "Sora", even though most of them were physicially unable to do so.
