Work Text:
The first time they realize something's going on is when pro hero Dynamight walks in their classroom to talk about his job.
That is certainly not unusual; UA usually invites pro heroes, so they let them know how it's like to work as a hero, the risks they have to take in an actual battle against a villain or simply do a training exercise with them.
So it's not unusual to see a pro there; Midoriya-sensei has invited a couple of them the past few weeks. Dynamight is certainly not the only one.
But he's the first one to talk to Midoriya before the class starts in the hallway and smile fondly at him while he does. Some of the students watch the interaction with fascinating interest, mostly because they have only seen the explosive pro hero on tiktok videos or the news and he doesn't seem like a very soft or kind person.
He's a good hero and clearly cares about the civilians he protects, but he doesn't smile at them the way he does to their teacher.
Some of them say it's because Midoriya used to be in the same class as Dynamight, but others argue that has nothing to do with it because they both were with pro hero Shoto too and Dynamight often frowns at the man with mismatched eyes.
"Class! Great explosion murder god Dynamight is here!" Their teacher chirps, smiling from ear to ear. "You can ask him as many questions as you want!"
They do ask him a lot of questions; he's a great pro hero, albeit a bit grumpy, especially around fans, but he's excellent at his job so more than one of the students want to be like him.
Dynamight spends the majority of the time with his arms crossed and a serious expression; he smiles a few times, but all of them are because of something their teacher says or does.
It's quite interesting.
Midoriya walks him outside when the class is over, and all the students watch through the window as they reach the parking lot.
Dynamight smiles again, but this time he moves even closer towards the teacher and presses their foreheads together.
"They're totally dating!" One of the female students says then, but she thinks everyone's dating and she's often wrong so none of them take her seriously no matter how suspicious Dynamight's behavior is.
Midoriya comes back inside, cheeks slightly pink, but none of his students makes a comment about it.
Then, a few days later, as one of them glances quickly through the window, they spot Dynamight with something in his hands that looks suspiciously like a bento box.
"Sensei, your Dynamight is here!"
"What?" Perhaps Midoriya is too distracted and confused to notice the way the girl phrased that, but the other students do and decide to keep using it too.
By the time he opens the door, the pro hero is right outside with the bento box.
"You forgot this at home, Izuku."
"Oh! Thank you, Ka–Dynamight!" Midoriya says, cheeks coloring with a soft shade of pink.
"Anytime," the pro hero smiles in a way he only does when he's talking to their teacher. He pinches Midoriya's cheek softly before turning around. "See you tonight!"
"See ya!" Midoriya grins from ear to ear until his eyes glimmer with joy. Then, he goes back to his desk and says, still drunk with happiness. "So, where were we?"
The most important piece of information they get from that interaction is that they definitely live together.
Dynamight comes back a few days after that, but only to pick Midoriya-sensei up. He's in civilian clothes and rides a bike that makes him look like a bad boy type rather than a pro hero.
Curious as always, some of Midoriya's students get closer to the parking lot to watch them.
Then, there's the sound of an explosion coming from the inside of the building and the first thing Dynamight does is to push Midoriya behind himself, ready to use his own body to shield the teacher's.
They all know there's nothing to worry about; the students in the support department like to experiment and their ideas don't often work so there are a couple of explosions every week and they're used to it now.
Their teacher places a hand on Dynamight's broad arm to calm him down; it works like a charm.
"It's okay, Kacchan," he mumbles quietly, although some of the students around manage to hear. "Remember the things Hatsume used to do? We have someone like her this year."
"Kids..." Dynamight rolls his eyes, before pulling Midoriya closer to himself. "Let's go. I'll make dinner."
"Can I choose?"
"You always choose katsudon, so no."
"Kacchan, please!"
"Tch! Fine!"
Alright, maybe the girl's right this time; they're probably dating.
***
It's actually a boy the one who ruins everything and on the worst day possible.
He asks the most dangerous question right before the training exercise begins, the one in which everyone is going to fight Dynamight at the same time because he's going to act as a villain.
"Don't be too harsh on them!" Midoriya chuckles, putting a hand on the pro hero's shoulder.
He smirks back at him.
"I won't make such a promise," he says, but they all have learned after a month of observation, that Dynamight often does as their teacher says.
"Midoriya-sensei, are you dating Dynamight-san?"
There it is. The dangerous question. Midoriya makes a distressed sound before turning so red it makes him look like a strawberry.
Dynamight smirks, looking way too pleased out of the sudden.
"No, we're just friends!"
And the smirk vanishes, the light in those red eyes does too and Dynamight is suddenly very grumpy again.
But he looks a bit hurt too.
He's ruthless after that and defeats them all of them in a couple of minutes.
They all can tell there's something wrong with him, even their teacher, so he follows him outside when he starts rushing out of the gym.
Despite feeling terrible (they're not physically hurt, but the easy defeat shock them and made them want to train harder), they run outside too, to see what's going on.
They can't tell what they're talking about, but Dynamight and Midoriya are definitely speaking. The pro hero has his arms crossed over his chest and he looks grumpy, but mostly in pain.
"Kacchan..." their teacher takes a few steps closer and puts a hand on the other's cheeks, right where his scar is. "I didn't know."
"How could you not?" Dynamight huffs, although he doesn't seem as irritated as he was a few minutes ago. "It's not like I was being subtle!"
He's absolutely right about that; the students agree completely.
Sadly, they're talking in whispers again; the class can't tell what's going on, but then Midoriya-sensei gives him a quick kiss on the lips that has Dynamight's cheeks turning slightly pink.
"I'll see you tonight, Kacchan."
The grin the pro hero gives him in return is everything they need to know they're finally on the same page.
***
"Sensei, your Dynamight is here!"
Midoriya grins from ear to ear at that and rushes towards the entrance only to find the pro hero walking in the gym already.
"Ready for me to kick your asses again?" The pro hero smirks at the teenagers.
"Kacchan!"
He's different this time; he gives them more opportunities to hit him, and when they can't, he explains to them what they did wrong and why it'd be dangerous to act like that in a real fight.
They learn a lot from him that day.
Midoriya-sensei watches him with a proud smile on his face.
It's different now. The way they act around one another is different; the lingering stares, the intimate smiles. The students suddenly feel like they're intruders.
At some point, Dynamight curses, Midoriya scolds him, but he forgets about it quickly because the pro hero pulls him into his arms like he can't stop himself and presses his lips against their teacher's.
"Kacchan, not here!"
"It's your fault for looking so cute."
Even though they're happy for them, some of the students roll their eyes at that. Then, like he's been summoned, Aizawa-sensei walks in and pulls a suddenly grumpy Dynamight out of the room.
"I told you. No PDA!"
"I'm sorry!" Midoriya apologizes on behalf of both of them. "It won't happen again."
"Don't make promises you can't keep," Aizawa scolds him, and this time the students agree with him.
They don't believe their sweet teacher either.
***
Only a few weeks after that, they see it; the beautiful ring on Midoriya's finger.
"Congratulations on your engagement, Midoriya-sensei!"
Their teacher nods, smiling at them as happy tears slide from his eyes.
That's probably the reason why pro hero Dynamight has been in such a good mood lately. He doesn't frown at his fans anymore.
They make a really good couple.