It's all about the character.
"What interests readers is not so much what happens, but who it happens to."
That's how Peter Rubie says it in How to Tell a Story.
And ain't it the truth.
Would Gone with the Wind be the same story without Scarlett O'Hara? Or Rhett Butler? Change either character and it becomes a different story.
What about Huckleberry Finn? Do you think the story would be the same with another character in the title role?
I've seen it so often in writing advice: the story grows out of the character.
But of course it does. The characters I write don't always go where I want them to either. That's how I know they're real. Whispering in my ear.