Hiding in Plain Sight
Wonderwyce Magdera was far from stupid. People just assumed that Aizen-sama was the only one capable of putting on a façade, and it was a reasonable assumption, looking at his track record- but really. With his reputation, would he have put up with Wonderwyce for so long if he really was as useless as he appeared? Would he assign him to important tasks if he was incompetent? The answer is no.
And of course, it makes perfect sense for Aizen-sama to trust one so like himself. It is the nature of the strong to exploit weakness, the most important quality of which is to trust blindly. If one appears to fall into one of the predictable boxes with which they define and organize their existence, they are automatically put into it, and it takes more effort than you may think to reassign them.
It has been told time and time again- first impressions are the most important. So, if you can cast one that is to your advantage, you can always use the advantage of that lingering doubt about your true intentions. People want so, so badly for things to be predicable, to understand a world that resists their futile attempts at organization, that they will believe even the feeblest of lies if it plays into that hope. They wish with all their hearts that the truth of the world is not cruelty, and so they will make every effort to ignore it if at all possible- and they do his work for him, excusing his own slip-ups (Damn that Urahara) and yet still continuing to believe.
They are the stupid ones. The irony is so satisfying.
Aizen-sama understood that little game of Wonderwvyce's the first time they locked eyes. And while he may not trust him, he also does not trust his Espada. After all, they still are part hollow, and Aizen-sama isn't that dumb. It is all one colossal game of intrigue, and he is a spy among traitors. He plays with them all, "friend" and "foe" alike, manipulating them as he sees fit and then contenting himself with watching carry out his wishes without even knowing what they are truly doing.
A far more interesting way to idle away the time than chasing wholes.
And, those dragonflies taste damn good. Roast songbird is also quite tasty.
But, once again it is their loss for not looking outside the box.
A/N: Wonderwyce amuses me. And forgive if I misspelled his Magdera or whatever. But really- he must have some purpose for Aizen to put up on him? And why else would he send him out with U-chan and Grimmjow and Yammy? All of them are likely to have been, or are, Espada. And I for one never suspected Aizen before I got ahold of spoilers.