Zoro is a cambion, which means he feeds on sexual energy. A small crew like the Strawhats, its not normally enough to keep a cambion satisfied, but Sanji happens to be an abnormally sexually driven cook so it usually works out okay for Zoro. At least, it works out alright until Sanji finds out that Zoro's been taking energy from him through his dreams. For Sanji, he's trying to wade through the confusing mess of emotions for a certain marimo after a surprise kiss on the battle feild. It's not easy to do on a normal basis. It certainly isn't any easier when the man he has deeper feelings for is a cambion. Then everyone learns how important it is to keep their local cambion fed, for if they don't, someone might get eaten. literally.

Midoriya Izuku was born with a quirk: the ability to summon and bind demons from an alternate plane to do his bidding. With only a few days left until the UA entrance exam and still no offensive-type demons in his arsenal, Izuku makes a desperate attempt at summoning one corporeal, a feat he had never before attempted. He'd say it was a success but, he doesn't actually know if it'll be more a help or a hindrance. Especially since Bakugou Katsuki is, well, kind of a shit.

Saving people, hunting things: the family business. Modern AU: the Nies are hit by a demon's death curse, which is NOT fuck or die - it's fuck AND die, a kind of reverse cultivation curse that's usually directed against cultivation partners, destroying their golden cores little by little every time they fuck. NOT a clever curse to use against brothers! ...except that the curse comes with a chaser: its targets share blisteringly horny sex dreams every night, as a way of encouraging them to go ahead and give in to the whole fuck-and-die schtick. Awkward. So it makes sense to search for a cure to the curse, right? Especially since the cure might actually help stabilise Mingjue's golden core. Obviously they have no intention of actually boning once they've got rid of the whole fuck-and-die curse... (...for the life of me I can't remember who suggested a Fuck AND Die trope on Twitter many weeks ago - evidently it has been living rent free in the back of my head ever since, though, and so here we have some Niecest.)