Worst-case scenario for a sex pollen type scenario: it's not a pollen, but a virus which mutates very rapidly, so it can be caught again and no cure can be developed. And it gets transmitted as easily as the common cold, maybe has an incubation or contagious but no symptoms period. Obviously would require lots of research about disease transmission.

The more you practice magic, the more you have to use it. So...there's somebody who has to use magic. Normally it's not a problem; they just use it for little things throughout the day, most of them not anything that would be noticed even by somebody looking right at them. But then there's something tha prevents them from doing magic: a curse, or they're trapped in a warded house, or something. They're not alone. And because they can't use magic, it builds up in them. The first side effects are small, easily ignored, usually a sign to use magic. Later, they start acting like they're on drugs. If it goes on long enough they'll die.

The apocalypse comes, and it's even worse than a lot of people are expecting because, hey, in the real world all of the fruit and vegetable plants they sell (including, or perhaps especially, those sold to commercial farmers) are designed to be sterile--as in, after the crop that's currently in the ground gets harvested, if there isn't any more seed to be bought then we're not going to have anything to live off of other than domestic animals and whatever we can find out in the wild.

In alternate-history Kansas, all of the fields have hedgerows around them. (because in our world there are trees, and they're there for windblocks, right? So why not hedgerows?)

There's a something which is a huge danger because to trap its prey/victims it creates a perfect representation of a place that feels safe & happy to them, with something to help make them believe it. It works better with people who feel very safe most of the time, but almost everybody has a place where they feel safe or that they can be convinced to feel safe in. Naturally distrustful people and people who have learned to be distrustful can pick up the minor glitches within a few hours, when something pings their memory wrong and they start pulling threads and unravel it. So, if you knew this all, and then you saw somebody get whammied and barely pause for a second...wow, must suck to be them.

Some form of entertainment, written as if it was by aliens, for aliens from the same culture. So, for instance, if they were writing their version of Stargate SG-1, all of the references to the Simpsons, mythology, etc. would be explained to the exact same degree that they are in canon!SG-1. And maybe idioms would be different, too, depending on how far you want to go with it.

It starts out being written like the MC's a latchkey kid: she gets herself up and prepared for school in the mornings, makes her own food (or has it prepared for her, so she just has to reheat it/take it to school), the house always seems to be empty except for her. Maybe there are occasional notes to her. But eventually it becomes apparent that she isn't living with any adult--maybe with a ghost (not, I think, a family member)? While she's on the verge of sleep she could her it then, and give further evidence to the "not squatting in the house" misleading. Not as the main plot, because she knows about her circumstances so it's not a mystery, but as an around-the-edges thing: she goes off every day having her adventure, and comes home to this empty house and loving notes. Maybe it affects how she acts, like she absolutely insists on being home by a certain time, and the reader is very confused about why until she comes home late one day and the walls are bleeding or something.

Hm, might be fun to do it as a coming of age thing, and/or if she gradually realized that their relationship was abusive and successfully managed to get the ghost to change.

Crazy alternate universe, where males can only reproduce with males and females can only reproduce with females, but either pairing can produce children of either gender; this pattern extends to any species which does not reproduce asexually. Give careful consideration to social changes--e.g., like IRL each couple would need at least one partner to work to support them, back through history, so gender discrimination is not going to have ever been like it is or was here; also, everybody is gay is the only thing that makes sense here.

Protagonists are a straight couple in the modern day, extremely aware of how lucky they are to be living in a time when it's legal and to some degree accepted for them to be together and hoping that someday soon it will be legal for them to get married.

In TV, books, and movies, it seems like every detective/PI/cop deals with the big crimes--murder, rape, art theft, etc. So what about one that's about cops/detectives who deal with minor crap, or are traffic cops or something? With the focus being a lot more on the people rather than the cases. Stick in a supernatural element, preferably a lot more understated than in other shows: each of them has a supernatural secret and doesn't know their partner's secret (though it doesn't drag out for too long; eventually they find out because otherwise they just look stupid), but most of their cases are normal, mostly boring cases, and their supernatural secrets only occasionally affect their lives. Put a limit on how often they have to draw their guns, and how often the supernatural causes more than minor irritation, and stick to it.

It's the equivalent of the '60s in Urban Fantasy World. The race issues are mainly between werewolves and vampires (and humans?) rather than blacks and whites.

MC is a police detective, but they also secretly run/rule the city's supernatural community. Most of the time it works out, but now they're working hard on an important case, and having to deal with important stuff going on in the supernatural community. Are the two connected? Will she be able to deal with both at the same time? When will she ever be able to get some sleep?

A vampire in some sort of anti-addiction program.

Somebody who has the kind of powers that are basically "you must fix this problem or your life will continue to be disrupted" gets so jaded that he stops doing it because he wants to do good, stops being outraged at horrible things, etc.

MC develops powers of a type that can't be proven (psychic visions or something, not telekinesis or anything easy to prove) and starts hiding them from everybody. Only later do they learn that their sibling has had the same power for longer, and has been hiding it all along as well.

Several centuries/millenia ago, MC was given the job of ending the world/stopping the end of the world by [date]. But she's like most of us, so she procrastinated. Now there are only days/weeks left to finish her project, and she hasn't even started to make plans.

Fantasy; original, crossover, or timetravel.  For whatever reason, a kid who's had a very good and thorough education in the use of his/her powers (they've had them since birth, and since their parents were involved in the supernatural they had the benefit of learning how to use them along with everything else like walking and talking; by this point, they use their powers very fluidly and naturally) and an adult/older teen who's new to their powers, clumsy with them and possibly afraid, have to live/travel together.  Post-apocalypse, maybe?  Not many other ways to fling together an adult and child who don't know each other previously.  The adult has to do all the adulty things--protecting the kid, making sure they have enough food, etc.; but the kid has to teach him what he needs to know, because the situation's dangerous enough that they need to use their powers to stay safe.

A devoutly religious person, who has built most of their life around their religion, is turned into a vampire.  Now they literally cannot do anything having to do with religion- crosses burn them, an invisible force field keeps them from entering churches, etc..  How do they reconcile the two?

A story with very relevant POV which keeps switching- eventually the reader learns that the true POV is of an alien hopping from one mind to another, or a mindreader.  And possibly that they're actually the bad guy everybody's been talking about.

God of Life

Character: personification/god of Life.  Very creepy.  Sees it as a game between humans and himself, which he always wins (as in, they die).  "Whenever the gods are playing chess, the only human move is to change the rules. Everything else is defeat."

Criminals after the apocalypse

After an apocalypse, the survivors band together and don't make a big deal about who did what beforehand- and some of them were Bad People, before.  But it's not worldwide/somebody somewhere has the resources to help, and when the aid starts coming in the outsiders get all "criminals!" about some of them.