Board Thread:General Discussion/@comment-31283382-20131101162239/@comment-5553481-20140720130610

Stefan (Shikai - "Rust & Shatter") wrote: Gacsam wrote: 1. Arrancar is a "transformation" that apparently any hollow can achieve through tearing off their masks, which would bring out a question - why don't all of them do?

Maybe it's not common knowledge among Hollows, or perhaps they know that which Shawlong came to realize; that if an Adhujas is damaged, it can never evolve into a Vasto Lorde, and tearing off their masks could be considered taking damage. So maybe they only tear off their mask after they've lost all hope of becoming Vasto Lorde? Well, yes, AFAIK when you become Arrancar, you can't 'evolve' anymore, so you could say that it's technically the 'end' of the hollow evolution, meaning when you become Arrancar at Gillian, you stay Arrancar at Gillian forever, which could explain why Aaroniero, even thought he has "devoured thousands of hollows" and is Espada still is considered a Gillian arrancar.