***Just a thought...if Fai really is teetering...do you think an event relating to Ashura (maybe they go back to Celes by accident, and see the imprisoned king?) could push him over the edge, and he does something stupid like stand at the edge of a cliff, wanting to jump?***
Yes.
What I think is that they will absolutely end up in Fai's world, at which time Fai is going to either totally freak and run, or become totally mute.
I think maybe he already knows that Ashura has a feather, or it's occuring to him.
He will realise that either he is going to have to face Ashura to get the feather, or he will feel that his fear of Ashura will prevent him from getting it and maybe try to leave the others, this may be he breaking point.
I don't know, I have plenty of ideas on this. But I think they do have to end up in Fai's world at some point and Fai has got to go against Ashura.
It'll all come out then.