Fandom: My Hero Academia. Story idea: A secret academy for villains. I know it's stupid and silly, but I just find the idea neat, so might you.
"Welcome to H.V.A, the Hidden Villain Academy," Shadow Lurk, the penumbra villain, said to the ground of students, or rather potential students, in front of him. He looked them over as he spoke. Some of their quirks were obvious just by looking at them, some wouldn't be able to tell until they showed them off.
"As you know, in order to combat the increase of powerful heroes in this world, the villains have banded together for the purposes of training even stronger villains. Under our watch you'll be made powerful. We do not care what your motives are.
"Power, gory, wealth, thrill, lust; whatever your end game for your path as a villain, you'll be trained to take what you want, groomed into perfect villains. The only string attached is that if called upon by another villain, you must help them to combat whatever hero has come onto their trail. Strength in numbers. Just like the heroes take victories by covering each other and acknowledging the powerful of comradery, so to will we."
"The dorms here are co-ed. We do not care who sleeps where nor do we care what happens when the lights go out, so long as we don't have to hear about it. If something, or someone, goes missing, just do not leave any evidence and you will not be punished. Anyone in this school too weak or too stupid to avoid getting stolen from, exploited, or killed, didn't deserve to be here in the first place.
"But of course, not all of you will be able to attend this school. We'll only be accepting those who can prove that they have the potential to survive in the world of heroes and villains, and so we've prepared an entrance exam for you.
"I'm sure many of you may have heard about the entrance exams at the hero schools, mock battles in fake environments where any damage to your body can be healed afterwards. Our exam will be different.
"There will be real stakes. This exam will test your willingness to commit crime, your abilities to get through high pressure environments, and even your combat skills if it comes to it. You will be at actual risk of injury, arrest, and if you truly mess things up, death.
"All of you already have trackers on you so we can monitor your movements during the exam, so if any of you attempt to rat us out to the heroes for leniency, you'll be killed by a remote shock before you're able to. If you're captured, you will only be broken out by us if you've proven that you deserve it.
"Come forward now and collect your missions. They're simple, we don't want any of you facing off against All Might on your first day, but I cannot promise a hero of some kind will not arrive during your exam.
"You'll just have to find a way out of the situation if they do. Strength, stealth, speed, intelligence; whatever gets you safely passed the heroes and back here will work. I look forward to seeing which of you make it."
If made into a full story... well first it would involve me making actual characters for the story. It was probably be equal parts action from a villain's perspective and high school romance between the students, and I'd try to strike a balance between action and lemons. I'm willing to except ideas for villain student/teacher OCs.