This is a position that I've defended for years -- and sometimes gotten into heated arguments about (once with some network execs during a discussion of notes on a project that they had commissioned me to write -- always a bad idea).
The idea that either -- every story has to have a character arc or --
the even more pernicious idea that every *good* story has to have a character arc, is just a bunch of bull.
This is how I look at it.
You can have a central character that undergoes some significant change. We all know lots of movies like that.
Or you can have a central character that stays the same and a secondary character or characters change (think of something like Rio Bravo).
Or you can have a movie where nobody changes -- like, for instance, The Maltese Falcon.
It has nothing to do with inferior or superior movies or story-telling. There's no hierarchy, with the "no-change-at-all" movies at the bottom, and the "secondary character-change" ones in the middle and the "protagonist change" ones at the top (or even better -- I love the note where the execs want everybody to have their own special little character arc -- the more the merrier).
In every story, the protagonist embodies a certain idea -- he is the living representation of whatever the theme of the story is. And by the actions he takes and the decisions he makes you, the writer, are going to explore that theme, through him.
Maybe your protagonist is a pacifist, and you're going to explore whether that "idea" -- the idea of pacifism will work.
So you test that idea, in the living form of your protagonist.
Start off with him as a pacifist -- or maybe not. Maybe he's violent at the beginning and he becomes a pacifist. Then test that idea through the events of the story. Does he stick to his pacifism, or do you put him in some situation that makes him conclude -- no, sometimes you have to set it aside in favor of something more important.
If you're telling one kind of story - if you want to tell the story of a pacifist that sticks to it -- if that's your theme -- then you're telling "Gandhi" -- and he doesn't change. He starts off committed to this idea and he remains committed to it. Others are violent and become non-violent. THEY change around him. He -- because he embodies this theme -- that pacifism is the correct path -- he stays the same.
But maybe you want to tell a different story. Maybe you want to show that, under some circumstances, you have to abandon your pacifism.
Then you're telling "Sergeant York" -- and then you're telling the story of a violent person, who finds God, becomes a pacifist, goes to war, refuses to fight -- only to realize, at a critical moment, that sometimes you can save more lives by fighting than by refraining from fighting.
Gandhi, embodying a particular theme, stays the same.
York, embodying a different theme, must change.
Now, obviously, both of these movies are based on real people, so you're stuck, to some degree with their real lives -- but the point would be the same if they were wholly imaginary -- if the events of those movies were happening in Middle Earth.
Whether a character changes or fails to change depends upon the theme that you are exploring.
A character may embody a change *toward* -- that is, he embodies, at the beginning, an incorrect view of the world, which must change in order for him to achieve whatever it is that he needs to achieve.
Or, a character may embody a correct view of the world, a view that the events of the movie will challenge -- will tempt him to discard, and that character must hold on to that view of the world in the face of those challenges, in order to achieve whatever it is that he needs to achieve.
Both are equally fine.
Both can yield stories that are equally deep, equally moving, comparable works of art.
NMS