I've been spending my week copyediting The Bastet, a short collection of contemporary stories I wrote to explore a single, absurdist idea: What is life really like for a catboy or catgirl? Which then requires a backstory: where do cat people come from, such that they can exist in an otherwise recognizable contemporary setting?
My solution was to play with a common trope, The Magic Goes Away. In the Bastet Universe, for a brief time (~400 BCE to ~200 CE), Magic worked. It worked pretty well. It ebbed and flowed, and sometimes skilled practitioners found their power almost completely inacessible, and other times so overwhelming they created disasters or just incinerated themselves. The "real" in-universe explanation is that magic works everywhere in the universe; it's a mundane feature. Except in our region of space: 30 million years ago, a supernova either swept this space clear of whatever it is that turns will into reality, or filled it with a magic-dampening something. We're the only place in the universe where something with a lemur's consciousness and a need to escape a hungry tiger doesn't automatically turn into nuking the planet. For that 600 year period, Earth drifted through a space where magic worked somewhat, but not reliably. And now, in our 20th century, we're left with evidence of magic, but no way to work it. The Bastet are an Egyptian alchemist's wild dream of a fierce soldier race, but we all know how bad cats are at following orders.
I have been tempted recently to write more in this series. It's my only extant contemporary series, and the universe is a fantastic setting for other ideas. What magical creatures other than Bastet are there? I've had two ideas, one involving a tentacle monster, the other involving futanari. This slice-of-life smut which tries to take a wider look at how the world reacts to this sort of strangeness is my favorite kind of writing, since it's about alienation and acceptance, which is pretty much how I've lived most of my life anyway.
I worry, though, that by writing about other ex-magica creatures, I'll be diluting the original vision I had for The Bastet, which is taking catgirls seriously. I think I did okay (even if half the stories ended up M/M, and the other hand M/F; I realized I don't have a single F/F catgirl story in the whole collection!), and I have more ideas in that theme alone, but would it wreck the original purpose of the series if I asked, "What other weird stuff did the great alchemists of ancient China, Rome, Egypt, and Mesoameria come up with?"