User blog comment:Godisme/Deicide...Ah I can't keep track anymore/@comment-1906999-20100709142003

The reason Aizen is doing this, I assumed, was that he had gone power hungry. Like you said, we don't know how Aizen was before he was trying to get power. He was even working on this plan 110 years ago, according to TBtP. So, we never saw the first moment Aizen actually became the bad guy, since he was the bad guy already on Sogyokou Hill.

But you raise another good point. Since we know nothing of the Spirit King, what if it ISN'T bad Aizen is trying to kill him? As far as we know, the SK is more powerful than Aizen, but yet we know little to nothing about him.