I wonder if there are any long-term implications for a planet having a moon that orbits opposite the planet's rotation.
I've got one of those in a story, and it's okay, a Wizard Did It, but I'm not sure if this scenario is unstable because of how their gravity interacts. At the very least, maybe it's slowing down the rotation of the planet slightly?

Oh God figuring out the phases of the moon is going to be even less fun

Thankfully the local Wizards What Did It don't have moon-based magic and there's no werewolves so the phases being weird doesn't actually affect anything.

The tides being unusual does, though thankfully only a little

I wonder how werewolves work on a planet with multiple moons.
Do you turn when any one of them is full? When all of them are full?
Or does each werewolf have a chosen moon that they're linked to?

Idea: a Nightfall type situation where a planet has like four moons and their cycles only align every X hundred years, meaning no one has noticed that the werewolf gene has now spread to over a third of the population

Silly idea: so the most accepted theory for why we have a moon is that it split off of earth when we got hit with another planet. One of the issues with this theory is that in most simulations, this would result in an earth with two moons, not one. But we only have one, obviously. So either there's something we don't yet understand, or we just got one of the unlikely rolls of the dice for planetary formation.

But what if the real answer is werewolves?

Earth used to have two moons and the second one was linked to werewolves, causing them to shift. Early human civilization was constantly at risk of werewolf attack, because they're the ultimate infiltrators: you can't build a city wall to keep them out, they just show up in your city every full moon.

So the magicians (from back before The Magic Went Away) hatched a terrible scheme: to save human civilization, they blasted the second moon out of orbit.

Unfortunately this magic second moon is also where their magic powers came from, so while they ended the werewolf threat, they also destroyed magic itself.

But civilization eventually thrived without werewolves and magic. This is what let agriculture as we know it take over: the transition from hunter-gatherers to farmers happened because we were finally free of werewolves.

But despite the fact it's been over ten millenia since we banished the second moon, oral histories of magic and werewolves linger on in myth.

And here's how you make it a story and not just a setup: the orbital parameters of that lost second moon have just been discovered, because...

It's on the way back. It's in a comet-like orbit that takes it way out of the solar system, but eventually it'll return, and when it makes a close pass of earth, we expect a bunch of descendants of werewolves are gonna suddenly transform.

We've got a year to plan. Magic is slowly coming back too: can we learn enough in that time to stand a chance against the werewolves?

Although, some potential bad news from science: there is a population that has between 1-4% of genes that come from a race other than Homo sapiens sapiens: some of us are descended from hybrids between H. Sapiens Sapiens and H. sapiens neanderthalensis.

And Neanderthals lived in Europe. So guess which humans are mixed? Those of European descent!