Short form: Please do NOT write to me-or-us with story ideas.
1 We are not as forgetful as some folks assume we are. It helps to bear in mind that if it’s been “years” and you haven’t seen X THING / CHARACTER / LOOSE END addressed “yet” — that’s probably only two or three books. You read much faster than we write. The smart money says we probably haven’t “forgotten.” We just haven’t gotten there yet.
2 I make it a practice not to read story ideas sent by readers. This is not because I don’t love you. It’s because there’s a long, bad history in writing regarding people suing writers for having “used their idea” without giving them credit/compensation/the firstborn/whatever. I don’t have time for this kind of nonsense, so it is my policy to throw out, unread, ideas for future storylines in any of my working universes.
And, yanno, I’m not just being an Old Meanie, here. This policy serves you, too. Say, I’m planning on doing X in the next novel, and you write to me all eager for me to X in the next novel. What happens, if I read your letter? I have to throw X out, because of #2 above, and you will never get to see how it plays out.
All I’m saying is — trust us, yeah? We know what we’re doing — in large measure, anyway.
Here ends today’s Public Service Announcement.