[Zieveraar]

True, I hope that is explained somewhere along the line, what we have seen of him does show that he isn't just plain "evil", there's more to it than that! (I hope anyway) I'm not so sure it is done solely because it is beneficial to him alone, although it would be odd if he was only following Aizen because he was ordered by Yamagata to do so.

Although when we are going to read about it exactly is a good guess, considering the current chapters, I'm not exactly sure what to expect anymore.