Why Characterization Is Overrated

In Iron Man 3, fourteen members of the President’s cabinet are sucked out of Air Force One, after a Mandarin attack.  Tony Stark, a.k.a. Iron Man, flies in to rescue them in a daring aerial rescue, saving them from certain death with only yards to spare, and dumps them in the water.  They cheer as he flies away.
…they cheer as he flies away?
Look, these people have literally been in terror of dying for the last three minutes, and weren’t sure they were saved right up until they hit the water and realized their heart was still beating.  They’d be adrenaline-shocked, enduring the beginnings of PTSD, barely able to move.  A weak “thanks” would probably be the best any of them could give.
And yet even assuming that they were compos mentis enough to process everything that had happened, the President had just been kidnapped and Air Force One destroyed in what has to be the most successful terrorist attack in American history.  At least two of their friends had been slaughtered in front of them, one speared through with a souvenir.  They might be happy to be alive, but they would no sooner be cheering happily than we saw the victims of 9/11 whooping “GO FIREMEN!  WHOOOO!” when they got hauled out of the World Trade Center.  Their applause is completely inaccurate characterization.
It’s also perfect for the scene.
What’s perfect is what’s perfect for the scene.
Too many beginning authors treat “accurate characterization” as though it were some sort of magic formula for fine writing: just stay true to the characters, and you’ll have a good narrative.  But that’s no more true than any of the other million inflexible “rules” for writing scattered throughout the Internets.  In this particular scene, we the audience are thrilled by Tony Stark’s ingenuity and derring-do, and dammit at the end of the scene we want to feel the triumph of Tony’s magnificent accomplishment.  So the traumatized survivors cheer like Tony just won a football game… and this is precisely the correct thing to do.
Likewise, maybe your lead character should have PTSD after everything he’s been through.  Maybe she has every reason to snap angrily at someone who doesn’t deserve it.  But does that characterization serve the scene?  Is having your lead scream at someone for no reason going to yank the reader’s sympathy away when you need the reader to feel empathy for your protagonist?  Then maybe, just maybe, you skip the “biting someone’s head off” bit and have the character remain reasonable and calm.
In fact, if you pay really close attention to a lot of comedic works, the motivations of even the lead characters fluctuate from scene-to-scene.  The Big Bang Theory is one of the most popular shows on television, and Sheldon its most popular character… but he oscillates between “God, Leonard, how could you spoil that comic for me?  You know the rules of spoilers are inviolable!” and “Who cares if I spoiled that novel for you?” depending on what comedic purpose it serves.  (And you can’t say, “That’s just Sheldon being self-serving”; Sheldon is established as a character who treasures rules and conventions above all else, except when it’s funnier than he doesn’t.)
(And if you don’t like Big Bang Theory, read Terry Pratchett’s work.  Most of his characters shift a little to fit the circumstances, although his best characters like Vimes and Granny Weatherwax do tend to revolve around certain inalienable axioms.)
And I think we can all point to longer series where characters evolve as the author figures out who he wants them to be, and then you go back and read the first novel in a series and everything seems subtly wrong because the characters are acting in ways that they simply wouldn’t do in later books.  That’s because it was more interesting for characters to be that way, and thank God the author didn’t stick to her guns and say, “No, on page 10 of book 1 the character did this, and that’s the way they must always be.”
The point is that accurate, consistent characterization is merely another tool in the writers’ toolbox to serve a larger purpose… and sometimes the correct call is to look “What should happen logically” in the eye and ignore it.  Sometimes you change someone’s reaction to mirror the emotional tone of the scene, as in Iron Man 3.  Sometimes you do it to crank up plot tension, as Sheldon’s shifting characterization does in Big Bang Theory.  (In fact, one of the reasons why Big Bang Theory is as successful as it is is that Sheldon’s character can shift effortlessly to become an antagonist to anyone.)  Sometimes you do it to preserve or manipulate emotional reactions to a story.  Sometimes you do it because the alcoholic falling off the wagon for the fifth time this novel isn’t interesting any more.
Now, if you push inaccurate characterization too far, you have howlers like Prometheus, where everyone acts like idiots.  But as a writer, you’re not shooting for accuracy; you’re shooting for verisimilitude.  You don’t need to describe every blow in a fight, you don’t need to describe every touch in a romantic scene, and you don’t need to keep to absolute gritty realism unless that’s the tone you’re shooting for.  And even then you’re probably going to fake some things.
The truth is, characters are as mutable as dialogue, or plot, or prose.  They adapt to serve the greater purpose of “What you’re trying to accomplish in this scene.”  And yes, like bad dialogue or plot or prose, done badly it’s glaringly obvious that something’s wrong, but that doesn’t necessarily mean that good characters always hew the line.  Quite often they’re subtly manipulated in ways you don’t notice, and when that happens the author has done her job correctly.