User blog comment:LordLuminous/Fairy Tail Chapter 411 Theories and Predictions/@comment-7418318-20141123173547

The title makes me think of people who don't particularly like each other working together because it's of benefit to both of them... but I can't really see anything like that happening in the current situation, except perhaps the relationship between Oracion Seis and Crime Sorciere (you help us gain our freedom and we'll help you take down Zeref perhaps?).

Leaving the title aside, I've got the feeling that Lumen Histoire will absorb both the effect of Face and Memento Mori into itself. This will likely kill Mavis, if she's still alive to begin with, but save Natsu and Gray and probably also restore Erza's senses back to normal.

It might also stop Kyouka from being killed by her connection with Face, but then she was also stabbed, so she's probably going to die either way.

There's no real basis for this theroy, it's just a feeling I have.