The first chapter is the one part of a novel that is two things simultaneously:
1) The most exciting to write.
2) The least likely to be shared.
I adore writing hooks. And that hook should be in the first chapter (if not the first paragraph or sentence or word). It’s usually the core of the idea that made me want to write the novel in the first place. That random spark of character or what if or theme or image that blossomed into a huge, gangly pantheon of a new-born novel.
Everything is new and exciting in the first chapter, I’m getting to know characters, writing by the seat of my pants, thrilled at how the words are forming to describe and talk – is the idea working? Are the characters possible? Getting along? Is there blood yet?
Then of course, I write the rest of the book and realize I didn’t know the characters well enough when I wrote the first chapter, I didn’t put in foreshadowing, so-and-so can’t say that thing because they don’t turn out to have known anything about it… etc.
So the first chapter gets rewritten. If I’m lucky, it’s similar, but better. If I’m unlucky, every single word is scrapped and I start with different characters, different moment, different everything.
But that’s part of the fun and excitement in itself.