Prologues in fantasy and SF books used to be a pet peeve of mine. I couldn’t see the reason for them. Most of them I’d come across in my reading seemed to merely be history lessons or summaries of events which didn’t seem to have anything to do with the story. So I stopped reading them. Oh, I’d take a look, check out a few lines, then, if it seemed to be another history lesson, I skipped over it the first time I read the book. Sometimes, I didn’t go back and read it even when I read the books in question again. Sometimes, I never, ever got around to reading the prologues of books because I was far more interested in the story contained within starting from Chapter One.
Catastrophe did not befall Civilization.
I have a pattern. If it’s a book by an author I’m unfamiliar with, I may reread the book a number of times, but I won’t read the prologue until I’ve read enough other books by that author to trust their writing. Writers with whose writing I’m familiar, I may or may not read any prologues in their new books the first time through.
The rest, I still check the first few lines.
Because of the number of “history lessons” I came across in various genre books, I didn’t see a point in having one. Often, the historical stuff about a world/country had little or no bearing on the “present” depicted in the book. Just as often, when I finally did get around to reading the prologue, it turned out to be stuff which could have been included in the main narrative as backstory or other ways. In fact, the only book I’ve read whose prologue turned out to be pertinent to the story in an important way but which would not have worked as part of the narrative in the book and could not have been adequately or well-managed in the main narrative was that in Not Your Father’s Horseman by Valerie Griswold-Ford.
And that’s the prologue that changed my mind on them. I could see a good reason to include one in books now. Don’t get me wrong. I still check the first few lines, but now if it seems to be a history lesson or a summary of past events, I still skip it. Still, even these days, many prologues seem to be unimportant to the main narrative. Or unrelated. But now I’ve seen a perfect example of when and why to use a prologue in a book.
So, when I realized I had a scene that fit nowhere for one of my planned books, but it pertained in an important way to the main narrative, I was willing to write the scene out as a prologue. I may not use it, but I like knowing it’s there just in case I need it, especially since I don’t think much (if any) of the overall narrative will come from the MC (but non-pov) in it.