You may have run into the GM who loves his or her story so much, wants to see his or her story appear so much, wants to be praised for his or her awesome story so much ... and the problem is, you have to guess what the story is as you go along, and play it out like they want, or they're bummed out. Or worse, you don't even have to guess because they send cues at you a blind toad-man could read, and you have to follow those cues, or they're bummed out. Substitute "bummed out" with "resentful" or worse.
This is what people are complaining about when they say, "I don't want to have to violate my character to make a story." Taken at face value, that makes no sense: a plot results specifically from the actions of characters, after all. But when you're doing time in a Typhoid Mary's game, then yeah, someone with a story in mind is demanding that everyone else subordinate their characters to his or her intentions.
One person, typically the GM in a traditional GM/players construction of play, makes it impossible for anyone at the table to play with a Story Now agenda except for him or her, often greatly desiring for such play to seem as emergent as possible. Armed with a variety of Force techniques, as well as any number of misconceptions about The GM and The Story, this person tries to make all the characters' significant decisions for them (De-Protagonizing, specifically Railroading), and perhaps with ostensible commitment to The Impossible Thing Before Breakfast.
This is not a case of Agenda Clash, nor of Techniques Preferences (although both may compound the problem), but simply a Dysfunctional, self-defeating failure of technique that originates in the crucial "Let's play this game together" component of Social Contract. The Typhoid Mary is trying to play Story Now, but they are mistakenly determined to ensure that the other people at the table don't screw it up, for example by playing their characters as they'd prefer to play them.
Where it goes (nowhere good)
If anyone else at table really wants to play Story Now, he or she may well become a Prima Donna, and a tug-of-war over "the story" will ensue. This leads either to the player being labeled "disruptive" and leaving the group, or to a charismatic coup by that player and the expulsion of the old GM, unfortunately all too often resulting in the ascendance of a new Typhoid Mary. (Ask me how I know ...)
The people who continue playing with a Typhoid Mary GM cope first with Participationism: "He makes the story, we go along with it." Which tends to break down in this case, because the GM harbors the (vanishing) expectation that the players will become Story Now go-getters. Therefore he wants exciting and emergent themes, but since he always wants players to go the way he wants, he continually shuts them down, so he enters a spiral of dissatisfaction. The group then tends toward Zilchplay: "He seems to like it, I get to say stuff for my guy once in a while, it reminds me a little bit of how much fun I had when I started role-playing, and 'game night' is a good excuse for a low-pressure hang-out with my friends."
Summarized in 2004: Narrativism: Story Now