Disclaimer: I do not own Bleach. That honor belongs to Tite Kubo.
Warnings: Spoilers for the Soul Society Arc
Ise Nanao knows that she could have done better. If she was Aizen Sousuke, Soul Society would already be at her mercy and the Shinigami dead or dying at her feet.
For all his plots and schemes and for all his power and intellect, in the end, Aizen Sousuke is still an egotistical idiot. He revealed his plans with little or no prompting, showing his true colors far too early in the game. Or perhaps he had simply grown tired of the charade, tired of having to mask his true nature. After over a millennium of it, she would be exhausted as well.
Nevertheless, she can't help but shake her head at his mockery of an attempt at world domination. He had the entire world at his fingertips, and he threw it all away for a plan that may or may not work out in the end. All he had to do was wait patiently for just a while longer, and it would have all come to him with little or no effort on his part.
Certainly, he had some convoluted plot that made perfect sense in his mind, and it most likely involved faking his death, only to return in full force later on. However, if Kurosaki and his friends were enough to disrupt this masterful scheme before it even got off the ground… well, it couldn't have been very good to begin with.
And Nanao can't help but think that she could have come up with a better one.
Truthfully, she already has.
Had she been Aizen Sousuke, she would have simply waited for the old man to die. Honestly, Aizen could have easily helped him along without making it seem too suspicious. The captain-commander is positively ancient; his death can't be that far into the future.
And after Yamamoto-soutaichou was dead, Aizen would have been the logical candidate to assume his position. In all honesty, Aizen was the only real choice for the next captain-commander.
With Urahara and Yoruichi-sama now gone and Yamamoto's own grandson, Isshin, dead, there is simply no one else to fill the role.
Undoubtedly, Ukitake-taichou would make an excellent commander, but with his failing health, he didn't stand a chance of being selected. Only a complete moron would want a supreme leader who could keel over and die at any moment.
Her own captain, Shunsui, is too much of a lazy drunkard to even be considered.
Unohana-taichou is level-headed and powerful enough for the position, but her station as fourth division captain commands too little respect.
Soifon is too moody and quick to anger, too much of a sullen and self-centered teenager. Also, she has only been a captain for a little less than a century, not nearly long enough.
And Ichimaru was far too creepy, not to mention too new at the post.
Likewise, Hitsugaya-taichou would have been a serious contender in a few centuries, but he is simply too young and too new in his position. No one wants a commander who doesn't look older than their own children.
Zaraki-taichou is too bloodthirsty and blunt.
No one in their right mind wants Kurotsuchi as the captain-commander. Soul Society would have been mutilated beyond recognition within a decade.
Komamura-taichou is too unsure of himself. He can't even stand to let people look at his true face.
Tousen's literal and figurative blindness put him out of the running. Further, although he was a captain, he wasn't a particularly powerful one. The commander has to be strong enough to stand up to any challengers.
Truthfully, although he is also a relatively new captain, Kuchiki-taichou is the only other person who could have filled the position. In a few decades, he would have been a serious candidate. However, having the head of one of the four noble families as captain-commander is a political disaster waiting to happen. Chamber Forty-Six would have had an aneurysm just thinking about.
It is never a good idea to give so much power to a single individual. As such, the chances of Kuchiki-taichou being selected are slim.
But Aizen, serene and kind Aizen, was just perfect for the role. He was level-headed and calm in the face of danger, powerful but compassionate, and he had certainly been a captain for significant amount of time, long enough to satisfy any naysayers. He was well-liked by almost everyone in Seireitei and had served as a friendly moderator in disputes for centuries. He had no strong political ties to any particular group or family. And most importantly, he was a favorite of Yamamoto-soutaichou.
They may as well have presented the position of captain-commander to him on a silver platter.
He never needed to execute Kuchiki Rukia or even kill all of Chamber Forty-Six. All he had to do was silently slip up her one night, use the device Urahara had fashioned to retrieve the Hougyoku, and then return to his division. Afterwards, he could quietly create Arrancar at his leisure without having to worry about anyone finding out, while simply sitting back and waiting for Yamamoto to finally die.
It was that simple.
And Nanao can't quite comprehend why such a dastardly mastermind could not figure that out for himself. But then, she supposes, he could not have been that much of an evil genius to begin with. Or perhaps genius simply isn't what it used to be.
After all, Aizen had never even thought to ask her to join him.