|Remember what happens next?|
+Christian Blouin pens at least a GURPS 303 article on using social reactions and influence against PCs. Any time you’re “compelling” the characters to act a certain way, you need to be somewhat cautious, but still, it can be done, and often is an important part of a majorly fun plotline
Consternation about “player agency” only applies if the player feels she’s been denied agency. If, as I did once with a game of mine, which was a totally “this is a railroad adventure” prequel session to set up the main campaign, I pulled a player aside before a session and said “you’re going to hit the climax here; at one point, you’re going to get hit by a big magic user with a staff. At that point, your character’s soul will be plucked out and imprisoned Elsewhere; a demon mage will inhabit your body. At that point, are you willing to just unload on your fellow PCs? It’s dramatically appropriate to kill them all.”
Why yes, hes he was more than willing to have such an awesome end to the adventure. I didn’t force the role on him, he accepted it gladly. But his goals were changed.
Anyway, Christian writes some great stuff here, and it’s worth checking out in full: