Thanks to the good advice from L.D. Parker in the comments, I resolved last week’s plotting dilemma by deciding to interweave the narrative from the trigger character and protagonist’s point of views. I’ll start with the initial “hook” scene I have in mind for the first chapter, then do an intro chapter with the protag, then alternate back and forth throughout the book.
I tell myself that even if it doesn’t work the way I want it to, I can go back and do whatever I need to fix it (probably drop the trigger character and focus solely on the protag), so long as I make it through the first draft.
With that problem solved, I finally started writing up the outline, character sketches, etc for the new book in Scrivener. This means taking all the notes I’ve jotted down — some handwritten, some typed up in Evernote, some dictated into my phone — and bringing them together in one place, and imposing some sort of order on them.
It’s the last step before I actually start writing, and it gives me a visual indication of holes in the plot, of weak points in the story that’s developing. For example, I can already see that I’m going to need a lot more background for my protag than I have worked out so far, simply because the number of their scenes aren’t balanced against the trigger character.
With luck, I’ll have the initial plan written up and into Scrivener by the end of next week, and then I’ll be ready to plunge back into the blank page and start swimming toward the finish line.