A/N: This fic was originally posted on my AO3 on January 13th, 2021, under the same author name and the title: "Mild-Mannered School Teacher/Adrenaline-Junkie Vigilante" (this fanfiction-dot-net did not accept the / character in the title, so I slightly altered it for the site).
Chapter 1: Morally-Justified Violence Might Actually Be A Decent Stress Reliever
Fuyumi's first act of vigilante justice was an accident.
It had been, to understate it, a bad day for Fuyumi. She started her morning late, and barely had any time at all to get dressed and get to work. She forgot to put on an extra layer, and so was shivering as she walked. The temperature wasn't even that chilly, most people she passed weren't wearing coats, but Fuyumi always ran cold. At the school she taught at, the second graders wanted to do anything but cooperate. They ran around screaming, and even her kindest pleas went unheard by the rambunctious children. Normally nap time was her break from the activity, but three children were resolute that they were not sleepy at all. Normally Fuyumi could talk a child down from their stubbornness long enough that they would start yawning and lie down 'Just because Ms. Todoroki wants me to! Not because I'm sleepy!' That usually did the trick, and everybody would be asleep in minutes. But when three whole children were convinced that nap time was a plot to strip them of their freedom and rights, they fed energy off of each other and Fuyumi couldn't keep them all down. And of course their complaints made it impossible for the other kids to sleep, so by the end of naptime nobody had gotten any rest at all, Fuyumi included.
With all children at their maximum crankiness level, things got a little off the rails. Some kids slept during storytime (which Fuyumi allowed, better than nothing after all) while others couldn't pay any attention. Some of them even started wandering to the playtime corner, completely ignoring Fuyumi's reading. Recess was even worse. One of the kids wanted to re-enact a scene from All Might's career, of All Might carrying dozens of people out of a burning building. The best way to re-enact this, of course, was to have their favorite teacher pick every single child up at the same time.
Now Fuyumi had been working on teaching communication skills to her students all year. And if they had been paying attention during any of her attempts to teach it, perhaps they would have kindly requested that Fuyumi participate in this heroic re-enactment. However, the kids communication skills were still, to put it kindly, a 'work-in-progress'.
And so all of them jumped on her at once without any warning.
Fuyumi wasn't weak by any means. Her family had their own private gym, and in the rare instances where Dad wasn't training Shouto there, she could sneak in and exercise a bit. Perhaps it was a bit silly, but Dad got her in the habit when she was younger, and if she went longer than a week without working out some of her energy she would begin to feel lethargic.
Trying to catch eight leaping children while another eight were leaping on her back, however, was a struggle even for her. She managed for a few seconds, muscles aching and screaming at the effort and legs shaking as the children shifted her center of balance everywhere, before collapsing on the playground.
Then she had to chastise the kids, and that just made them more upset. One of them, with a pufferfish-like spike-ejecting quirk, had even used it on her in his frustration. Fuyumi dodged the spikes with a sigh, blocking a few with hands encased in ice, before sending the kid to the principals office. She then had to excuse herself to the restroom to wash her hands in warm water so they wouldn't be numbed in ice forever. When she got back to the classroom, the kids had taken her absence as an opportunity to wreak chaos. Fuyumi had a lot to say to them after that. More than one kid left school crying.
And all of that was just the first part of her day.
She came home to the unfortunately familiar sound of Natsuo shouting at their Dad, something about Shouto's current training schedule being unsustainable for Shouto's health. Dad responded with curt remarks about how Natsuo hadn't even graduated from high school, so he wasn't qualified to make that call. Fuyumi had gone up to Shouto's room, assuming that Natuso's outburst had to be triggered by something.
Shouto was bandaged, with bruises peeking out between the white strips of cloth. She was relieved that Natsuo had at least treated them. Shouto watched her enter with furrowed brows, but asked to be left alone when Fuyumi tried to comfort him. She left his room with a sigh.
Natsuo and Dad were still yelling, now Natsuo was telling dad he should have let Shouto go to junior high school instead of homeschooling him, so he could have the chance to be a little less fucked up.
Oh Fuyumi definitely had to stop that yelling. She was right by Shouto's door, surely Shouto could hear it too. She made her way to her arguing family members, and discovered Dad had gone into 'Endeavor-mode', with flames erupting from his hair. That meant he was really mad.
Fuyumi physically stood between Dad and Natsuo, pleading with both of them to cooperate. Dad countered with some words about respect. Natsuo reacted by trying to get Fuyumi to take his side against Dad. Fuyumi agreed with Natsuo, but she didn't want to take sides, she wanted them to stop fighting for once. Dad expressed his anger by making his flames flare, filling the room with heat. That made Natsuo stumble back; he had been the recipient of enough burns that fear overwhelmed his anger.
Fuyumi never burned. Even when she had been younger, training with Touya and Dad, before they lost Touya and Shouto became Dad's new project, she hadn't been burned by either of their flames. If anything, the heat that filled the room dispelled her ever-present shiver and allowed her body to relax a bit. With the warmth giving her strength, she held her ground and pleaded with her father, reassuring him that Natsuo was just worried, she knew Dad was trying to do what he thought was best, and perhaps if everybody stopped yelling...
When the Endeavor flames began to recede, Natsuo took the chance to start complaining again, criticizing Dad with reckless abandon. Fuyumi had to take some very deep, calming breaths to not start yelling at Natsuo herself for interrupting her efforts when she had finally calmed Dad down. Now she had to calm Dad down again, and probably Natsuo too if he was going to be stubborn about it.
An hour later Natsuo left, slamming the door behind him. Fuyumi could finally go and cook dinner, no longer trapped as the mediator and protector preventing the fights from going too far or getting physical. As she cooked, Dad complained that dinner was late, and she had to bite her tongue to avoid snapping back that it was his fault. Snapping at him wouldn't solve anything. She took a deep breath. Helpful thoughts, Fuyumi.
Natsuo came back in time for dinner, eating silently with a pissed expression on his face. Dad was also silent. Shouto didn't say a word. A few attempts to start conversation yielded stilted, one-word answers, before Fuyumi gave up.
She wasn't sure what exactly had caused her family to all fall apart. But day-by-day, things cracked and faded, people died or got sick, and soon she was left with just a handful, all angry at each other and ready to break with any stress.
She wanted a happy family. She didn't understand why nobody else seemed to.
After dinner she retired to her room, laying down and stretching her aching muscles. She was still sore from the stunt those kids pulled, and needed to rest.
Then the yelling started again.
She put a pillow over her ears, trying to drown out the noise. She probably should have gone down there, once again being the mediator. But frustration bubbled in her gut, and she was certain that if she went down now, all she would do is add more shouting to the mix, and that wouldn't be helpful at all. She wanted to shout at them to stop yelling, to stop fighting, to stop tearing everything apart.
For once in her life, she just wanted to feel like anybody else in her family was trying to keep it together.
When the yelling got loud enough that even her pillow couldn't drown out the sound, Fuyumi got up. She took slow, quiet steps down to the front of the house. Dad was probably too distracted to listen, but old habits died hard. She slipped on her shoes, remembered her thickest coat and hat, and left as quietly as she could manage.
She wasn't going towards anything, just away from the house. She wandered aimlessly; so long as her body was moving she felt like she was doing something instead of being stuck frozen while her family collapsed.
It was dark out, and Fuyumi wasn't actually sure where she had walked to. There were few streetlamps, but Fuyumi was in the mood to brood in the darkness. Anger rose with every step she took. She was always the one who had to stay calm, the ice-quirk user who cooled down everybody else. What was she supposed to do when she became the angry one? Her feet were stomping on the streets, crushing some litter that blew by. It was only after she heard a scream that she realized she had perhaps walked into a bad neighborhood.
She was running towards the sound in an instant, passing by alleyways with squinted eyes to try and find the source. Not that she was looking to fight anybody, no she wasn't suited for that at all. She was just a mild-mannered school teacher. She had given up on being a hero a long time ago. She would just see what's going on, call the police (or perhaps Dad directly, then maybe he'd get a chance to work out his anger on criminals and give Natsuo a break), and get away from there.
When she finally found the source, her heart leaped into her throat. There was an elementary school girl, arms outstretched, standing in front of a little boy crouched on the ground. In front of them was a man dressed in black, knife in one hand and other hand extended to grab the girl and stop her screaming.
The police wouldn't get here in time. The time it would take to call Dad wasn't enough time. Fuyumi was the only other person around she could see.
She flung her hand out, and small quills of ice from her fingertips crossed the distance to prick the man's hand, aborting his attempt to grab the little girl. He jumped at the sudden interruption and turned to face Fuyumi. By then, Fuyumi had sprinted close enough to punch him in the face, years of being critiqued on her stance and form coming back to her in one-adrenaline fueled moment.
This man was much lighter than Endeavor.
He went flying back, head knocking on a stairwell with a loud clang before collapsing onto the ground.
Fuyumi stared at the man, knocked out, and the screaming finally stopped.
She turned to the little girl, who stared up at Fuyumi with stars in her eyes. When she spoke, Fuyumi saw there were gaps in her teeth, "Granny told me if I ever get in trouble, I have to keep screaming until someone comes to help me."
Fuyumi was still high on adrenaline, but got down to be eye-level with the child before responding, "You did great, I wouldn't have known someone was in trouble if you hadn't done so."
The girl preened, then turned to lift the little boy off the ground. He was trembling. "It's alright now, that man won't take you away, this lady saved us."
The boy sniffled. Now that Fuyumi had time to stop and look, she saw that he had horse ears and a long face. He must have had some sort of horse quirk or something. His response was a quiet, "Thanks."
Fuyumi nodded. "Do you guys live near here? I could walk you home."
"Yeah, we can walk by ourselves, though. Granny said my brother and I shouldn't let strangers know where we live."
With that, the little girl tugged her brother along down the street. Fuyumi wanted to walk after them, maybe tail behind just in case, but they entered a building almost immediately, so Fuyumi hoped that was their home.
She turned her attention back to the man she punched. She couldn't help but stare at her own fist, clenching and unclenching the weapon, marveling at how with just a little movement, a little force, she made the screaming stop.
And damn it was satisfying.
She could barely remember why she had been angry before. She had seen a problem, solved it in seconds, and now was basking in some well-deserved relief. It was a simple problem and a simple solution, unlike everything else in her life. She didn't have to plead and beg and crawl on the ground, at the mercy of people around her. It wasn't okay to hurt family, she had seen it happen more than enough times that the thought of doing it herself disgusted her. But when it came to hurting criminals... Well, technically, it was illegal, but...
Panic rose suddenly. This was illegal. She had used her quirk to help take him down, she had to get out of here. Before leaving, though, she made a quick phone call to the police, glancing at some street signs to tell them the location of a 'suspicious man with a knife passed out in an alley'.
Once she was far away enough that she couldn't be accused of being involved, Fuyumi looked up a map app to find her way home.
When she got back, she was exhausted, but at least nobody was arguing anymore. It was bed time for Dad, so the house was silent. Fuyumi tried to slip off her coat and shoes as quietly as possible, but the distant sound of Dad's door opening told Fuyumi that she hadn't been quiet enough.
He entered the foyer with arms crossed, but flames off. He was angry, but not furious. "Where were you?"
"Just out taking a walk." Fuyumi was not about to tell a pro hero she had just broken the law.
"Tell us where you are next time you stay out late," He spoke quickly before turning around, not allowing her any time to respond.
She sighed. It wasn't like she had gone out looking for trouble. But trying to defend herself was not helpful. Neither was moping about her Dad's emotional constipation. Helpful thoughts, Fuyumi.
So yes, that first spontaneous act of vigilante justice was an accident.
The second was not.