I didn't write The Six Elemental with any sequels in mind. It sounds crazy to me now – that I put all this effort into creating a future world with a detailed history and never thought of another story for it ("Twenty-One", in Sci-Fi From the Rock, was adapted from a scene that got cut early on). But, to be fair, I had doubts that I would ever finish this novel - I mean, I'd worked on it for over a decade - so the thought of writing a second was crazy.
But, on the other hand, I'd created an entire future world! Was I ready to just let it go? Surely there's at least one more tale in there that wants to be told...
For a while I wondered if there was another story to tell... Was there something I had missed?
Then I realized that there was a secret I'd placed in The Six Elemental that I never told the reader. It's not an obvious secret – it's more of a secret in the personal history of one character, which explains some of their actions – but it's there.
And maybe that's all it takes to spark an idea. Maybe all you need is a look or a glance or a word from a character, which you realize has more weight behind it than you thought. Then you think about this character and their past and their future, and what they might have gone through or who they might have met. And scenes start forming, and characters show up, and dialogue pops into your head...
And from that one, seemingly minuscule, thing you've grown a whole new story.
I mean, I've still got to write it, but that's a whole other kind of problem.
*Or maybe, if you're one of those people who likes to plan ahead, you've actually inserted secrets into your stories knowing that they could become their own stories. If so, please teach me the ways of future-story-planning.