A Soul Reaper captain went bad, decided to destroy the world or take it over. I'm not sure even he knows which. I don't know the whole story, but he started planning the whole thing way before I was born. I only found out about it right before I came here. He said he'd planned every step that brought me there. Implied he'd planned my whole life. Pretty sure he didn't, unless his plans included a talking stuffed lion and Rukia sleeping in my closet.