Board Thread:General Discussion/@comment-4115054-20140903063305/@comment-26475399-20150707022143

StealthBlade98 wrote: while i admit aizen is definitely highly intuitive when it comes to coming to possibly scenarios. Like using Orihime as bait to lure some of the strongest soul reapers away from the fake Karakura town fight. He's definitely highly intelligent on par with Kisuke but even so, i doubt he knew about that kido spell or knew to merge with his sword prior to being defeated. He seemed genuinely furious about the whole thing after ichigo defeated him

Yeah, he did seem genuinely furious in his defeat, i do agree.

When considering the facts upon which to build my theory, i also think about in the manga, when we learn of Masaki and Isshin meeting for the first time. We see Tosen mention her as not being part of the plan, and prepare to eliminate her for Aizen. But Aizen seemed to have seen it as a great and much more beneficial addition to the plan. It was a welcome surprise, and Aizen, almost seeming to foresee a better alternative sequence of events, went right on with the flow.

That being the main point i think of, i also think of how angry he seemed to be when Gin tried to kill him. He was all screaming and irate, and then comes his new form and it's, "I knew you would do that." Whether he found Gin out in the beginning, middle, or even toward the end to the point where Gin made his heroic attempt, Aizen obviously prepared for the possibility, and even then it still seemed to tick him off when Gin took a stab at it (pun intended).

His anger upon Kisuke's kido taking effect, i imagine could possibly just be that he thought he was on an unstoppable roll, and nothing could halt him at that point. Surviving the FGT, seeing his blade crumble as a sign that he was so powerful to not even need one anymore. Knowing Aizen, he could still use a defeat as part of the plan -- but maybe this detail wasn't as much of a welcome surprise. Especially considering the timing, which probably couldn't have been much worse, from Aizen's perspective.