So, I was flipping through book one of Tsubasa today, and I came across that one pannel where there are all the presumably-dead bodies in Fai's word. And this is just a theory, but, what if they aren't actually dead? What if all those people are sleeping, like Ashura? Yes, there's blood there, but Clamp faked us out with Syaoran and the clone "controlling" him, so it follows that they'd potentially do the same with Fai's past.
A lot of people, Del Rey included, seem to think those people are there in the aftermath of a battle, but Fai and Ashura seem to be very close and, on Fai's part at least, affectionate towards each other. So why would they fight? And if they *did* decide to fight each other, if some sort of circumstance turned them against each other, why get other people involved? Fai said himself that he doesn't want people getting hurt by getting involved with him. Now, admittedly this statement could have been made BECAUSE people have gotten involved with him and gotten hurt, but Fai seems like the kind of person who will do anything to avoid fighting. And frankly, in all the pictures we've seen of Ashura, he appears very gentle and not hostile at all.
So, that's my Fai-theory for the day XD