Or guide or cheat-sheet, whatever you want to call it. I did one yesterday, after reviewing copyedits for The Vision. Wouldn't it have made more sense to do that a bit earlier - you might ask - like, before you'd already written the two books in the series?
Yup. But I didn't think of it - didn't think I needed it - before. Mostly, I've heard of people doing a series bible for really complicated plots or world-building in fantasy series. The Mark isn't like that - it didn't even start out with clear intent to be a series. It was bought as a single book. Then my publisher bought another one. Will there be a third? Who knows?
But I knew I needed a bible while I was double-checking some stuff in The Vision for an earlier round of edits and found a small inconsistency in The Mark. I realized how hard it is to keep track of everything and everyone in any novel.
I'm not sure how anyone else does it, but my series bible is not a big, fat book. It's a couple pages, listing every fact I could find about every character and the timing of when things happened in The Mark and The Vision. That's the hardest part for me: the timing. It's incredible how easy it is to have a character do something one day, progress a few days so they can do the next thing you want them to, then realize it'd be the weekend and they couldn't possibly be at school, having that conversation. And, of course, flashbacks add a whole other dimension of trouble and I do love me some flashbacks in my books.
I think I need to use an actual calendar and mark story-days as I'm writing because I ususally find these mistakes during editing and then have to go back and rewrite whole chapters to make stuff fit. Annoying. But I guess that'll be for Book Four since Book Three's already drafted, mistakes and all.