!!SPOILERS FOR THE STORY AHEAD!! You've been warned, of course most of it is theory..there are plot points that might spoil it for you otherwise!
I've been contemplating the meaning of everything that's been going on lately, from Isshin's differed uniform compared to everybody else and him having "regained" his powers. I'm almost convinced he was a member of the Zero Squad or Royal Guard, and of course a previous Captain. Then a thought comes to a mind about Masaki and just how all of this ties in...bare with me for a second.
What if Isshin and Masaki were actually apart of the Royal Guard together? Then the two became romantically involved, thus involving in the pregnancy. It's possible that they decided to leave the Soul Society, because they felt raising Ichigo as a human boy would be better for him in the long run and thus they somehow resigned from their positions, but as a requirement for doing so...their powers had to be removed. So they were two normal human beings, of course with their Shinigami roots...but no different than a human when it comes to Hollows.
So they raised Ichigo and ended up having two daughters, everything was fine until Grand Fisher arrived and killed Masaki (who, because she lost her powers, was an easy target). While Ichigo was apparently the "focus" of the attack, what if Aizen orchestrated this like he claims he has everything else? Apparently he knew about Ichigo from birth, and in an attempt to either raise the skill out of him or do some other twisted act...he sent Grand Fisher in and disguised it as a "Hollow craving a strong soul". Regardless, Masaki's out of the way now...
It seems kind of Fishy (pun? I don't know x.x) for a Hollow like Grand Fisher to survive as long as he has considering he killed two shinigami, and then continue running on unscathed (if he becomes too much of a problem, I'm sure either a Lieutant or Captain would deal with him easily). He must have been a part of Aizen's little scheme of things from the beginning, thus turned into the "Big Bad" of a group of Hollows making him out as the mastermind of the whole thing in the beginning...while the true chessmaster was waiting in the shadows watching. Regardless, whenever he became an Arrancar turned by Iceringer...he was sent in again probably to test Ichigo but Isshin came in instead to settle the score...which was no more than a slight inconvience in Aizen's master plan of fights for Ichigo.
Eitherway, Isshin regained his powers (probably from talking with Urahara and learning of what was going to happen...considering his skills, he too needed to be ready) as well as Uryū's father, Ryūken. I can expect that with the arc there will be some telling of their relationship (as allies, similar to Ichigo and Uryū now) and Urahara.
Now this is just a theory of course, just putting it out there...
I've heard another theory (not my own, but from a board I go to) regarding Hikifune...as actually being Masaki. It would be an interesting twist, especially if during this arc that is supposed to deal with Isshin they showed Masaki as a Shinigami...but we don't know any details on what Kubo is planning until it happens. Again, all theories! TVthePunisher 00:44, May 29, 2010 (UTC)