Well this just kinda came to me a moment ago, actually this might have been though of before but I've never seen it, anyway: It was stated that replicas have hearts, fake hearts but hearts nonetheless at the end when Xion supposedly 'joins' with Roxas you think he might have gotten her heart someway technically making him a 'fake whole' of some kind?.....which would mean he is more of a real existence than Sora in those last days before he joins with him? 
