User blog comment:Xilinoc/Ch. 540 - The Sword Five/@comment-1904799-20130605203940/@comment-7092747-20130605205047

The revelation of Zangetsu actually being Yhwach does raise many questions, but I think to some extent you may be trying to complicate things that have actually been present from the start and only have been coming into light as of recent.

Yes, White is likely Hollow-Ichigo and that he was always present but only became awakened via the Shattered Shaft when Ichigo was forced through the enchroachment process. I don't think White and Zangetsu are actually one in the same but rather, as noted, Zangetsu has been acting like Ichigo's zanpakuto as a means of trying to suppress White.

What we have to remember is all Quincy descend from Yhwach which means, spiritually, he is apart of them all which explains why a part of his being was able to manifest itself within Ichigo in the form of Zangetsu. The overwhelming power of Zangetsu was what allowed him to dominate White and thus be pulled out during Ichigo's bankai training.

As for Rukia, her shinigami powers simply helped unlock the same shinigami powers that exist within Ichigo via his father. Simply put he is the son of a Quincy and Shinigami with a Hollow that exist within his being.