Let us continue on our journey into the depths of tabletop gaming hell, and look at another of it's denizens.
The GM breaker
"So, the NPC has clearly laid out the epic quest to save the East Kingdom, eh? I go West."
Some people just can't take a hint. This is not one of those people. The GM breaker takes the hint and bludgeons the GM with it.
The GM breaker is not the one to stand and argue rules. The rules in the book are not the rules that he is turning on his ear. It's the rules of the setting that are his weapon of choice. He's playing a game, but it's not the game you are running.
If you are running a high fantasy tale of heroes saving princesses and killing orcs, he will make a philosopher who finds issue with the assumption that the orcs are evil. If you are running a dark adventure with gritty characters working around the system of goverment in place, he will make the lawful stupid character trying to bring the other PCs to justice. If the party is good, he's evil. If the party are eco-warriors, he'll drive an SUV. If the plot is to the left, he'll go right.
And woe be to he or she who questions her on this, because he will go to ground arguing his right to play his character. Any concession he is asked to make is taken as railroading, and he will fight it every step of the way. He will pick apart your words on the subject. If you ask him to kill the orcs because they are evil, he will use this to justify killing the shop owner who gouges his prices, because he is evil as well.
If there is one rule this player is going to argue, it will be the alignment/morality system in your game, assuming it has one. Expect long winded arguements on what constitutes lawful, chaotic, good, evil, neutral, dark-side, humane, chivalrous, ect. The arguement has nothing to do with the way the game works or the rules in the book, and everything to do with the GM breaker's own views and objectives.
More often than not, the motivation here is control. The GM breaker has a game they want to play, and your intentions be damned. If they stick to their guns, the party will have to adjust around this character, and if then the GM is backed into the corner. The GM will have to make a 90 degree turn with his game and try to get back to actually running a consistent game. Then the GM breaker pulls a 90 degree turn in the opposite direction. Consistent story means the GM is in control, not the GM breaker.
The solution is generally decided by how stubborn this player is. At some point, once you realize that this is going to be a persistent problem, you have to sit him down and tell him that the situation cannot continue. If they have no interest in changing their behavior, they need to go to the store, buy Neverwinter Nights, sit at home and play that, because what this player needs is a single player game.