I made a theory when i first came to NB saying ichigo was apart of the royal family!! His Dad was in zero squad and became a personal guard for the king's daughter, but fell in love with isshin. so they had to flee SS because it was forbidden for a shinigami to get involved with royalty. And this would explain why ichigo's family are so weird and have a shit loads of spiritual energy. and aizen is just another oro =
Ps: here is a copy of my theory!!
"As you all know ichigo is a shinigami representative who naturally has abnormal strength and rietsu for a mere human, but is it just me or does anyone else think there is more to him than meets the eye? This was just a random thought but as i watched the anime and read the manga i realised that there was something going on behind the scenes. In the begining of the espada story we saw ichigo's dad wearing a shinigami outfit a cape similar to that of a captain, he was obiously rediculously strong and he said his powers we'rnt fully recovered yet. however, the real mystery is behind his mother, my theory is that ichigo's mother was apart of the royal family while his father was apart of a special squad assigned to protect the realm in which they live. I know this may seem a bit OTT but if people thought ishda was the last surviving quincy then how would you explain his father still being alive and well and also seemingly had history with ichigo's dad. This isnt any normal coincidence. Anyway, being in this position ichigo's dad fell in love with his mother and this would have been forbidden because of nobility laws, they then made the choice to flee to earth and use special substitute bodies made by kisuke that masks their rietsu completely making them untrackable. So i think that ichigo and his siblings are all technically related to the royal family and may possess other special abilities from their mother's side that we may not know about.
thanks for reading, MS"