User blog comment:Woest/The Light and Darkness of the Guild/@comment-7418318-20140316091038

When reading that I had two thoughts.
 * Maybe Lumen Histoire is the reason why Zeref started to value life. Rather than him starting to care by himself, this change of hearts could have been externally infused into him, which would explain why his caring for life messes with his control over his powers. And to play this futher, maybe the keys to Zeref's resurrection weren't useless after all, but they were responsible for Lumen's effects to be diminished to the point where Zeref is almost back to his old self.


 * Can we really be sure that Mavis was still alive when she founded FT? From Roubaul we know that it's possible to maintain a ghostly presence for more than 400 years in a way that everyone can see it and he was even able to do some quite amazing magic.

As for why Mavis is now only visible to FT members: Maybe some Zeref followers got tired of her meddling into their master's affairs and somehow cursed her to be invisible and while Mavis was unable to dispel this curse, she was able find a flaw in it, that allowed her to still be visible to those that carry the Fairy Tail guild-mark.