i think the vizard might be working for aizen,,,,,
Hirako said that,, We know. about the hougyoku, the arrancar and aizen sousuke we've known it all, long long long before you ever jumped on the stage,,,, and ichigo jumped on the stage when he meet rukia
and aizen been trying to get his hands on the hougyoku for years until he found out that it was in rukia body
and befor he knew that he was experimenting on hollow for years
then after ichigo saved rukia,, aizen took interests in ichigo, and sent Ulquiorra to kill him but Ulquiorra did not.. then grimmjow tryed to kill him,, and was stop be Tousen
then after that,, the vizards try to recrute ichigo,, until ichigo need there help to control his inner hollow
and if the vizards new all of that why didn't they just stop azien????
and vizard are more hollow then shinigami
and why didn't any of the vizard help ichigo when he when to the hollow world?
at least one of them should of went
the vizards use forbidden techniques to gain there hollow power and aizen is going the same thing,, they could be working together,, but i think they are working for Aizen cause he has the hougyoku