I've been thinking about an AU where the Octarians manage to avert the energy crisis before it begins, and as a result, never interact with the surface. This change butterflies into a world where everything looks a little better, but when you look deeper, turns out it's worse overall.
Mainly, the domes themselves. They've got ample power, spurring innovation into new ideas, and quality of life has never been better. But they're still in the domes. The sun is fake. The moon doesn't have the same magic. The clouds repeat themselves, the temperature is the same, and there's never been a drop of rain outside of agricultural areas. They're living in a flawed simulation of life, content to remain in a state of mild acceptance because everything is good enough. Who cares if the circumstances never align in a way that stops those mysterious disappearances? There's surely no pattern or thought behind them.
I'm writing a prequel with this kinda idea. Where they solve it for a short time but power corrupts even as there is very little of it.
I can't think of an AU name sadly, can only think of puns with ded like "deddomes" or something.
Actually that might be for a "dedfish stays in the domes" AU.