Crimson Longinus
Legend
In the example 'established fiction' it that the NPC said a thing. This doesn't change. What has not been established is the NPC's motivation for saying the thing.This rests on the conceit that a prep GM will be faithful to the established fiction while an improvisational GM will not be. That's the issue -- you're assigning virtue to one and denying it to the other.
When improvising and then tying things together later, you sometimes might have to reframe certain things that happened earlier, and if you do it well, it may appear as genius foreshadowing. "Oh naughty word, that crazy travelling cartographer we met three weeks ago had the similar glassed over eyes than these mind-controlled pawns of Prince Draculus! He was one of them!"