It starts, surprisingly enough, when the Bakusquad ditches the supervision of their foul-mouthed namesake. In hindsight, maybe that isn't such a surprise - Kaminari always does have the strangest ideas. And, whether this is a good or bad thing, Midoriya was in the vicinity when he voiced this one in particular. Little did the students of 1-A realize what they were starting.
"Hm?" The taller boy didn't even look up from his reading at Kaminari's question.
"I was reading about the top ten coolest vigilantes ever, and.."
"You should be reading To Kill A Mockingbird for Cementoss' class, you know." Sero grumbled.
"I know, I know, but it's boring!" The blonde complained, and if that didn't get Midoriya's attention, nothing would.
To Izuku Midoriya, To Kill a Mockingbird was a work of art. Racism was less prevalent since the appearance of quirks, but there were still plenty of parallels when it came to the treatment of those with so called 'villainous quirks', and the treatment of the quirkless. He and Shinso had already had almost a dozen conversations about the topic, after all.
As Midoriya was lost in thought, the conversation continued onwards, with both Asido and Kirishima now inserting themselves into the discussion.
"All I'm saying is that if we did a little vigilantism, we could help people, and get some more training when it comes to beating up bad guys" Kaminari was whingeing now, his idea having already been dismissed.
"Okay, but it's also illegal, and for good reason. Breaking the law isn't very manly, dude." Kirishima chimed in.
"Helping people who need it is super manly, though." Kaminari tried, but his friends weren't having it.
"You know," Midoriya's traitorous mouth began, "it wouldn't actually be illegal if was done right."
Kaminari's eyes lit up at that, and the Bakusquad-minus-Bakugou turned to him with rapt attention.
"Technically, because we have provisional licenses, that is," Midoriya began. "Legally, the provisional licences allow us to use our Quirks for heroic activities. That means that if he happen to see something going on, we are allowed to step in and help." He paused for a moment. "You'd have to be very careful to skirt the law, though." He added. Best not to give them delusions of vigilantism or anything, right?
"Thanks, Midoriya! That was good to know." Sero grinned.
It wasn't until later that day, when he spotted Kaminari, Ashido, Kirishima, and all Sero dressed in their hero costumes while being berated by Iida, that Midoriya realized he had made a terrible mistake.
"What exactly do you think you're doing?" The class president demanded to know, hand chopping and all.
Kaminari, the dumbass, decided that in this case, honesty was the best policy. "We're going on our patrol route!"
"We're gonna be vigilantes!" Ashido chimed in, because of course she would.
"Vigilantism is illegal, you know. As heroes in training, I assumed you would know that!" Iida cried out, clearly scandalized.
"It actually isn't, Midoriya said so." Kaminari defended. The four were all in the bottom quarter of the class though, so he couldn't be that surprised.
"And helping people because we can is a really manly thing to do!" Kirishima adds.
At the moment, it was all Midoriya could do not to cover his face and hide. Iida opened his mouth to speak, but Midoriya decided to get a word in first. He might as well bite the bullet on this one, and clarify the ridiculous misunderstanding.
"Earlier today, I uhh, explained that technically, thanks to our provisional licences, we could, err, perform actions that are like vigilantism, but they would be legal?" Midoriya tried.
Iida sent Midoriya a glare, which was a bit hypocritical really, seeing as Iida was potentially the last member of 1-A who should be lecturing others about how vigilantism is bad.
"You know what," Midoriya sighed, "I'll talk to them, Iida, alright?"
Iida, for his part, sighed. "Alright, Midoriya. I trust you'll ensure that they cease this tomfoolery at once?"
"I'll make sure that they don't do anything illegal, don't worry." Midoriya replied easily.
Iida raised his eyebrow but said nothing more, and headed back to his room.
"You're still gonna do it, aren't you?" Midoriya sighed. The trio of hero course students, literally in their hero costumes, nodded the affirmative. "Just... come to my room, I guess. I'll at least make sure you're being legal about this."
The trio, though it's mostly Kaminari, whooped and hollered with joy as they followed the green-haired hero-in-training to his room.
"So, let's note what you guys are planning to do isn't even really vigilantism, and is most certainly illegal." Midoriya begins, already pulling out highlighted sections of hero law from a binder hidden below the bottom drawer of his desk.
"I thought you said it was legal?" Ashido tries, confused.
"The thing is, that patrolling in costume is only legal for Pro Heroes, and comes with a lot of paperwork." Midoriya explains. "Also, Aizawa would probably expel you for acts of vigilantism, legal or not."
Kaminari, Sero, and Ashido all frown at this, but let him continue. As it turns out, that was the right plan - Midoriya has clearly done his research into the matter, and he points out the technicalities that surround the very concept of hero course students with provisional licences committing vigilantism.
"There isn't actually a precedent for this sort of behavior, either, from what I've seen," Midoriya explains. "So if we do get caught, we should probably assume the worst, honestly."
The worst is pretty bad: losing their provisional licences, potential jail time, expelled from U.A., disappointing All Might. Midoriya doesn't seem sure which of those four is the worst, which makes the trio of to-be-vigilantes laugh. They wouldn't all agree on which the worst either, though, so they only have so much room to judge.
"Midoriya?" Kaminari asks the question they were all wondering. "How do you... know all this?"
"Well, uh, I only got rescue points on the entrance exam to U.A., so I didn't think I got in at all. I did a lot of research on how to still help people without hero training. My quirk still hurt me back then, so I was considering fighting quirkless." This was a half lie - Midoriya's pondering of vigilantism was from long before the entrance exam, back when he was still truly quirkless.
"Helping others even without hero training, now that's manly!" Kirishima cries. Midoriya is beginning to think Kirishima just calls things he likes manly, but that's beside the point.
"Vigilantes typically don't have flashy quirks in the first place," the inheritor of One for All says instead. "Some, like Knuckleduster, are quirkless. With crime rates rising again, this was something I was already planning on looking into." Midoriya's complete nonchalance floors the other four. Midoriya, the sunshine child of Class A? A vigilante?
It's a few days later when it's finally time for their first patrol. Only Midoriya, Kaminari, and Kirishima are going on "patrol" tonight. Sero's quirk and Mina's (she refuses to be called her surname by a vigilante partner) appearance are too distinctive to add to the roster just yet.
As far as costumes, the trio wear dark jeans, black hoodies, and spray-painted masks. Midoriya even forgoes his red sneakers. Without them, he's practically a different person, Mina teases.
The group will exit the dorms through second floor windows about about two in the morning, and look for a safe way out of campus. In theory, the most difficult aspect of their vigilantism will actually be getting back _into_ U.A. safely, but that's a problem for another time. Or at least, a problem that they don't need to cover until a few hours from then.