You know that scene that you come up with in your head? You know, the one that you write ahead of time and spend hours thinking about because it's JUST. THAT. GOOD. You need it in your story because it'll add such drama and emotion and it'll be exciting to write and you know it's going to be exciting for your audience to read. It's THE perfect scene.
But then you get around to the point in your manuscript when it's time to debut this epic scene and...it doesn't fit.
It just doesn't go. And you love this scene and you've dedicated so much time to planning, but you can tell that it just doesn't feel like you thought it would. It feels out of place.
Usually it’s because of characters. In the world of storytelling, it is completely possible to write your characters out of character, often with really complicated consequences.
Something I learned in college is that characters establish themselves. And if you force them to do something that their character wouldn't do (based on who you've created them to be) you compromise their character and you compromise your writing. You have to let it flow, and ask yourself the hard questions of "would they actually do this?"
I just went through that. I had a character that I wanted to be quiet and heartless. I wanted it to seem like he had no soul. But as I developed his character and gave him a backstory and motives, I realized that how I wanted him to act wasn't the same as how he wanted to act. I was forcing him to be unnatural, which made it harder to write for them. He turned out nicer than I wanted him to—his gritty backstory had made him a better person than I wanted him to be.
So I had to let go. I had to let my character be the kind of character he was, not who I had dreamed him to be. And suddenly my story is easier to write, and I like it a lot better. I like him a lot better because he became a more dynamic character.
In another example, I had a character who lost her entire family. I wanted her to check out for a while, to be gone from the world. I wanted her to lie in bed for days and grieve, and to toe the edge of insanity. But then I started writing and she became a stronger character. When I got to the point of her losing her family, she was stronger than I expected her to be, and handled her grief with a stiff upper lip because I'd given her guts and a heart for others so early on. She loves other people more than herself, and even in her sadness, she can't stop paying attention to others. It's who she is, and despite my best efforts to make it seem like she was more deeply hurt than she was, she pushed back at me. It felt easier to write this character mechanically carrying her sadness like a trooper rather than forcing her to wallow in it for as long as I wanted her to.
I intended her to be a lamb, easily hurt, but she had this other strength that I hadn't considered as much as I should have.
So know your character. Know what they would and wouldn't do, outside of what you have planned. Sometimes they have a mind of their own, and do things that will surprise you.