I can't really make a better comment on this fic than what amyhit has already said, so yeah, that^. It is both gorgeously written and thoroughly disturbing.

I did find, however, that my suspension of disbelief wavered a bit around Mulder being so thoroughly convinced that Scully was actually his enemy. It was a very wise decision on the author's part to leave this part mostly up to our imaginations, but I do struggle to think of anything that would make him completely lose his trust in her the way he has here- something that would make him doubt her, okay, but this scenario is just so extreme that it was a little hard to swallow.