(I'm aware I might in over my head, but I just had this thought in my head and I was wanted to see what over people thought as well, but if I'm wrong I'm wrong).
There has been something I have been wondering about Tosen friend, the one who was killed by her husband because of some petty argument, we found out her husband was never executed for his crimes, in fact we don't know what happened to him, I think their is a slight possibility that Aizen was her husband, and perhaps he used his Zanpaktou, to control the senses of the central 46, to escape his fate.
I know it sounds farfetched, but here's 2 reasons why I think so;
1) Sosuke Aizen, we don't really know much of history, the first glimpse of his past we saw was when he was a vice-captain, we don't know what drove him to create the Hōgyoku, or drove him to his evil path, also he calls the Spirit King a "thing", it implies that he has meet the Spirit King.
2) Tosen friend, in the few chapters we saw her in her appearance is of a young, slender, beautiful woman with a scar/birthmark on her face and I have always wondered why did Kubo give this woman that mark on her face? I think its because we would be able to instantly identify if we ever saw her again, we may not know her name, but say if we did saw Aizen or someone else past and we saw her we would be able to know who she is straight away because of her mark on her face.
(It sounds a bit crazy I know, but keep in mind their have been a number of mind blowing reveals in this arc)