I think I know what you're getting at. That a player's actions should produce the dialogue, and that it shouldn't be pre-rendered? Like (here's a simple example) say the player jumps into a hallway where the ceiling is about to fall, a character would jump forward and pull him back or scream "Watch out!"?

But you're talking about advancing the story...like when the girl pulls back the boy from the deathly hallway, he realises that she does care or whatever (again, simple example). Am I right or am I missing out on something?