Bleach Crack!Prediction
Aizen isn't really THE BIG BAD. For some reason, I don't think there's exactly a BIG BAD there. And Urahara is definitely hiding something and in relation to that something, Aizen despised it so much => pretty much given, especially in 420+ chapters, I just don't exactly know what the Soul King is, but it may be something Lilith-like (ala EVA, maybe?). Probably monstrous enough for Aizen to say that he couldn't believe that Urahara would let SS be "ruled" by that thing.
>_>
>_>