User blog comment:Godisme/My Take on Isshin/@comment-1393830-20100328050807

But what if whatever is inside of Ichigo is stronger and or a compliment to the hogyoku. Natural and Artifical ways of creating Arrancar and Vizard. If you remember, Ichigo's hollow mask fully formed and his chain was fully encroached before he broke out of the mask. If there is something inside of him, my guess is it allowed him to maintain his shinigami and hollow powers once he had ascertained both, thereby creating a vizard