Lots of good questions this week, so let's finish with...
How do you approach tying up plot threads for your trilogy? It can be difficult to do for a single book. Doing it for a trilogy must be maddening.
You have no idea. There were times I was ready to rip my hair out.
I approached it much like I approach a stand alone novel. The trilogy had a core conflict that spanned the series, and all my plots had to connect to that core conflict in some way. Tying them up had to either help or hinder my protag.
One of the things that was so maddening was knowing I had threads out there that I couldn't just leave untied. A character from Shifter that I never expected to go back to had readers and reviewers wondering what happened to him. Minor characters were favorites. Things I tossed out there just for the scene stuck in reader's minds and became "important."
This was unexpected.
Now, I didn't have to go back and tie up some of these things, but I didn't want readers to feel like I forgot stuff or ignored the past for the sake of the future. (and I'll no doubt forget something and get emails about it) A lot of what the trilogy is about deals with past actions having future repercussions. If I wasn't going to let Nya ignore her past, then I couldn't either.
Identifying the Threads
First, I figured out what threads I had going in the final book. I had four or five things that needed to be resolved. Some were more issue than plot, but still important, like the romance between Nya and, well the love interest for those who haven't read it. (don't want to give spoilers) The romance doesn't really affect the plot at all, but it's something readers want to see resolved.
Next, I figured out what I needed to tie up from the previous books. Most of those came from goals Nya has (and had) and things she did in the past. Were there any long-term goals? Something they did that helped them win, but left something unfinished? One of my main plot points for book three came out of the final chapter of book two. Another personal issue for Nya also came from something revealed in book two.
I also had to think about what readers have asked about or commented on. Obviously I didn't have to do everything, but something I wrote as a throwaway detail in book two turned out to be pretty important in book three. But had a friend of mine who read the ARC not said "what happened to X????" I never would have done it. I'd forgotten about X. I actually have another one of those that I know I need to deal with for book three, but I just don't wanna. Getting it in there is going to be clunky and a pain, but if I don't, someone will notice. I'm pretty sure my editor will ask about it when I get my revision letter back.
I found making a list of my plot threads was helpful. It was an easy reference guide to make sure I didn't forget anything.
Connecting the Threads
This was the trickier part, especially if that thread dealt with another character. In the first draft, tying up those threads waylaid my plot so Nya wasn't driving the story so much as going along for the ride (bad, very bad). I had to take what I'd learned from that draft, and re-apply it so it affected Nya in some way.
Easiest way to do that was make it part of her goal, or make it an obstacle to one of her existing goals. Sometimes those character threads made good motivators for what Nya was already doing, and I could work it in there. (Like the romance) But I also had to connect the threads to each other, otherwise Nya would be running around with all this stuff to do and the story would feel disjointed.
You can do this with both external and internal goals, though. Some threads deepened something Nya had been struggling with internally, so it made sense to let that thread prey on her some more so she was forced to deal with it. Others were more suited to external goals and made better physical obstacles for her to overcome.
Tying Up the Threads
Know what I had to do was only half the work, though. I couldn't have everything resolving in the last few chapters or it would be information overload (a problem in the first draft actually). Things needed to tie up over the course of the novel so the ending built to the climax. Timing when a thread tied up was crucial, as it really affected my pacing. Thread resolutions couldn't come at the same time as plot reveals or resolutions, otherwise it wasn't clear which one the reader was supposed to follow. The plot got murky when I tried to do too much at once.
But those smaller threads were perfect for the down times, especially if they dealt with an internal goal. If there was a lot of action, I could still keep readers interested by resolving something they'd been curious about for several books. Even if it was only another step toward resolution. And subplots that were a tad weak were strengthened by connecting them to one of these threads.
It was definitely a juggling act, and I did need to do a lot of back and forth checking the other books to make sure I got everything. But as long as I kept my core conflict and main plot in mind when looking at those threads, I had something to guide me so it didn't wind up a tangled mess.