[Ardyn raises a brow where he stands, though Fynn can't see it. He's heating up some water now, waiting for it to boil. He already has the tea bag and its mug otherwise prepared and ready to go.]

I can't be certain of anything, if I'm to be completely honest with you. In the context of reality, they lack sense. For instance, those monsters I mentioned? I can tell you that nothing of the sort exists in our world, but-

[He pauses, a moment of consideration.] But I know that they were real. Are real? Difficult to say, and even harder to explain to someone fortunate enough to not experience these memories. They're too vivid. Too... lingering, in the mind.

[But he shrugs. It still wasn't proof of them being real, and Ardyn knows that. All he can do is explain how it felt, and a lawyer like himself knows that falls short of physical proof.]

If you're asking what the catalyst is, I suggest you start with the common factor. Retrospec.