Work Text:
Izuku was honestly surprised when Eraserhead asked him to guest teach for the man’s class at UA, and was hesitant at first, regardless of how much he trusts Eraser. “I would rather you join my class,” the man admitted, “but since you’re still being stubborn, I’d like you to help them learn.” And after working with the underground pro for over a year, after the man has taught him so much that has kept him alive, Izuku trusts the man more than he has ever trusted anyone in his life. He knows the man cares for and, more importantly, believes in him. So, against his better judgment, Izuku agreed to guest teach for a bunch of kids the same age as him.
He had a meeting with Nedzu to work out his permission to be on the grounds, what he was and wasn’t allowed to do as a teacher, how many lessons he would teach to start with, and pay. Izuku tried, he really tried, to convince both Nedzu and Eraser that they didn’t have to pay him — he agreed because Eraser taught him so much and he likely wouldn’t still be alive without the man, so of course he would return the favor by helping the man’s students — but Nedzu insisted on paying him like he would any other guest teacher at 2,000 yen per hour-long lesson that he teaches. He has a lot more freedom in his lessons than he would have expected, but apparently, UA is just like that.
Now, Izuku is entering UA grounds for the second time in his life, the first having been his meeting with Nedzu. The school is just as impressive as it was the first time he was here, but he doesn’t let himself get distracted by it. He has a class to teach. Once he’s in the school, Izuku ducks into an alcove to pull himself up into the vents, which connect to a hidden system of tunnels that even most of the teachers don’t know about. Izuku is incredibly glad that Nedzu gave him access to the tunnels because they have become essential to his first lesson plan.
Izuku makes his way to the vent over the 1A classroom, where Eraser is teaching a lesson to his homeroom. Izuku sets a stopwatch on his watch and drops out of the vents as quietly as possible. Luckily Eraser knew that this was his plan, so there isn’t even a moment of hesitation or hidden surprise as the man continues his lesson. Izuku keeps a close eye on the class, which he is behind. One girl, with earphone jacks dangling from her ears, turns around when his feet hit the desk to see him sliding the vent cover back on. He winks at her and holds a finger in front of his mouth over his fabric surgical mask, and she looks at him suspiciously for a moment before seeming to realize that her teacher must have seen the man in full costume at the back of the room, and is he didn’t raise the alarm, then she didn’t have to either.
Next, a student with six arms, one of which has an ear on the end instead of a hand, twists the ear toward the back of the room as Izuku is settling to sit on top of a bookshelf that is only half the height of the ceiling right under the vent, next to another shelf that goes all the way to the ceiling — Nedzu totally designed it that way. The student then turns one of his other arms into an eye which turns to look at Izuku and blinks at him, though the rest of the boy’s body shows no reaction. Nice.
Izuku opens the notebook in his hand and writes Jiro - 30 seconds , then on the next line Shoji - 50 seconds, extra points for subtlety, versatile use of quirk, glad he had been given some basic information about each of the students in the class, including a picture of them. Both of the students who noticed him first have quirks that can be used to enhance their hearing, which isn’t surprising. Then, Izuku notices that a purple-haired boy is watching him out of the corner of his eye, keeping one eye on the vigilante and the other on Eraser at the front of the room. The vigilante smiles and writes Shinso - < 1 minute, points for subtlety, first student without a hearing quirk . He has heard a lot about ‘Hitoshi’ from Eraser, and is glad to see he’s living up to what Izuku expected of him. Those three definitely pass their first test, but hopefully they won’t be the only ones. The class has five minutes to notice him, though the first minute would theoretically be the easiest because the only sounds he’ll be making now that he’s settled are breathing and writing, but those sounds could come from anyone in the class, considering that most of the students are taking notes on Eraser’s lecture.
After another two minutes or so, a dark shape pops out the back of the uniform of a student with the head of a raven. The shadow stares at Izuku for a moment before nudging the back of the student’s shoulder, causing him to turn his head enough to see Izuku out of one eye. The student turns back to the front of the class while the shadow continues to watch Izuku. Smart. Tokoyami - 3:06, using shadow for surveillance, goes in his notebook. The student behind Tokoyami, the one with red and white hair, watches this, then turns himself to see what Dark Shadow is looking at and sees Izuku. Being aware of the reactions of others is a good skill. Todoroki - 3:20, awareness of other’s reactions.
The next minute and a half are boring, and no one else notices him. With less than ten seconds left a girl with dark green hair stretches, and catches sight of him out of the corner of her eye. She startles and lets out a startled “ribbit.” Most of the class turns to look at her, but by the time they follow her line of sight, the time is up. Izuku writes Asui - 4:54, accidental, technically passes, and stands up. The class has gotten loud with exclamations of surprise and questions as Izuku makes his way to the front of the room.
“ Hellspawn, ” Eraser says in a warning voice, and the class quiets and settles in less than five seconds. Izuku offers him a small nod of thanks and hops up to sit on the teacher’s desk before the man continues. “This is UA’s newest guest teacher. He will introduce himself as he sees fit in a moment, but first, ground rules. You will treat him with the same respect you treat your other teachers. Any detention or other punishments he assigns will be enforced as if they came from any other teacher, even if he is not here to supervise them. And yes, his class will factor into your final grade, so you had better pay attention. Is that understood?”
There is a chorus of “Yes, Sensei,” from the class. Eraserhead then crawls into a bright yellow sleeping bag — oh, that was totally a present from his husband, wasn’t it? — and the class turns toward Izuku, seemingly unfazed. Honestly, that doesn’t surprise Izuku. Eraser patrols and fights at night, so staying awake the entire school day would likely be difficult. Izuku is glad that he only teaches for one or two hours a day when he’s here because he is also mostly a nighttime fighter.
Brushing it off, Izuku addresses the class. “Who can tell me how long I was in your classroom before Asui saw me and alerted the rest of the class?”
Three hands go up, though not everyone who noticed him. He calls on Todoroki first, wanting to see what his best guess is. “Three minutes,” the boy says.
“Closer than I expected you to get, actually. Why do you think that?” Izuku prompts. The boy only noticed him about a minute and a half before Asui.
“Because I know I didn’t notice you right away,” the boy says flatly.
“Good job being aware of your own shortcomings. Now you just need to work to improve on them,” Izuku says. He glances at the other two students that raised their hands. “Jiro, what do you think?”
“About four and a half minutes?” the girl says, though it comes out more as a question.
“Four minutes, fifty-four seconds, actually,” Izuku informs the class, and sees Shinso frown with an expression Izuku recognizes from himself. It is the look of someone who is used to and has come to expect discrimination in the classroom, even though it still hurts. To be fair, Shinso is the only one who raised their hand that Izuku didn’t call on, and with a vocal quirk he’s probably had teachers — and even foster families, since Izuku knows he was adopted out of the foster system — that wouldn’t let him talk and wouldn’t respond if he did. In fact, Izuku would bet that if he looked closely enough the boy would have a muzzle scar. He’ll figure out pretty quickly that Izuku isn’t like that, though. He notes Jiro and Todoroki’s answers in his notebook then turns to the purple-haired boy. “Shinso, who noticed me and when?”
Shinso looks surprised, but doesn’t hesitate long before answering. “Aizawa-Sensei noticed you right away, his eyes would catch on you for a second every time they swept over the class. I think it took Jiro about twenty-five or thirty seconds, and Shoji took less than a minute. Dark Shadow noticed you after about three minutes and alerted Tokoyami. Todoroki noticed them looking and saw you not long after. Su saw you by accident just under five minutes after you came in, like you already said.”
“And yourself?” Izuku says with a raised eyebrow.
“I noticed Sensei looking at you after about twenty seconds, I think,” Shinso says, looking away and sounding less sure than before.
“Eraser?” Izuku asks, looking down at the cocooned man.
“Yes, it took him about twenty seconds,” a rough voice comes from the floor without Eraser even bothering to make an appearance.
Izuku nods and notes both Shinso’s actual time and how accurate his observations of his classmates were. That bumps Shinso up to the top score for the exercise, with only six students passing. Hopefully, some of the other students will get some points in the next exercise, not that they seem to have realized they are being graded on this yet. “Now, raise your hand if you know who I am.” Shinso’s hand is the only one that goes up. “Well, since only one of you has an answer to that, we’ll wait, hm? What can you infer about me based on everything that has happened since I entered the room? Anything that has been directly told to you doesn’t count.” Only a few hands go up. “Oh, come on, you can do better than that. Unless you are completely unobservant, you have to have some kind of observation about me.” Hesitantly, a few more hands go up. Izuku picks one of the people who haven’t spoken yet. “Iida, one observation and what you can infer from it.”
“You are clearly very good at stealth. It is likely something that you have put a lot of time into!” the boy says, and wow, does this fifteen-year-old seriously still need to learn how to use his inside voice?
“Okay, that’s a start. I would hope that all of you had picked up on that, though,” Izuku says, noting Iida’s answer in his notebook under a quickly scrawled heading of Observations and Inferences of Me. “Kirishima, what about you? What is one thing you can infer, and why?”
“Well, you’re wearing a bunch of super manly gear, so you’ve gotta be a hero,” the red-haired boy says, and okay, sure, that’s one way it can be described.
“Thank you for your answer,” Izuku says, noting it down. “Mineta, your turn.”
“Wh-what? But I wasn’t raising my hand!” the boy says.
Izuku rolls his eyes. “I am aware of that. I never said I would only call on people with their hands up. Give me an answer. We can hone your accuracy later. What is one thing you can infer about me based on an observation?”
“Well, um,” the boy hesitates, then blurts out, “You’re never gonna get any girls dressed like that!”
Izuku snorts behind his mask and notes the answer down. It’s funny because he is very gay, and he’s not trying to pick anyone up, male or female, in his costume. It is designed to hide his identity and protect him from injury, as well as having easily accessible spots for all of his weapons on tools. “Okay, who’s next? Hagakure, what’ve you got?”
“Oh, um,” the voice coming from the invisible girl is soft. “You’ve worked with Aizawa-Sensei before?”
Izuku waits for her to continue, but when it seems that’s all she has to say, he prompts, “What led you to that conclusion?” He keeps his voice encouraging, not wanting his words to sound like a reprimand.
“You, um, you called him ‘Eraser,’ which mostly only people who know him professionally do, and he trusts you enough to let his guard down around you,” she explains, and yeah, she’s passing now. Those are good observations. She needs to work on her situational awareness still, because she didn’t notice him come in, but she’s observant. That’s good.
“Good thinking. That’s the most well-thought-out answer I’ve received to this question so far,” Izuku praises. “Does anyone want to follow that? I’ll pick someone with their hand raised this time.” Izuku watches in amusement as most of the hands in the room go down. Unfortunately, Bakugo is the only one who hasn’t spoken yet that still has his hand raised. This is gonna be fun, but might as well get it over with. “Bakugo?”
“You’re some kinda analyst of something, if the shitty notebook is anything to go by,” he says, and okay, that’s not as bad as he was fearing. Izuku guesses that it’s because the class was told to treat him like any other UA teacher, and from what Izuku knows, Eraser is pretty strict with his hero students.
Izuku nods and writes the answer down. “Alright. Anyone else?” Todoroki and Shinso are the only ones with their hands up, but he wants Shinso to go last because he just knows that the purple-haired boy will blow pretty much everyone else out of the water. “Alright, since no one new has their hand up, how about you, Todoroki?”
“You’re already grading us,” the boy says, his voice flat. “This is all some kind of test, that’s why you’re writing all of our answers down, right?”
Izuku smirks behind his mask, knowing it’s probably visible around his eyes even with the mask covering half of his face. “That is correct. I am grading everything that happens while you all are in a class with me. Luckily for most of you, today is mostly just getting a baseline for where you all are starting. Now, knowing that this is going toward your grade, would anyone who hasn’t spoken yet like to answer? You can’t get negative points.” Quite a few hands go back up, and Izuku looks between them. Eventually, he picks, “Ashido?”
The pink girl puts her hand down and says, “You’re protecting your civilian identity. Most of the teachers here teach out of costume, or at least go by their civilian names, but you’re in full costume and it doesn’t seem likely that you’ll tell us your real name.”
Izuku nods. “Good. Uraraka?”
“You must have a decent amount of field experience, for you to have been brought in as a teacher, and it has to be experience that is different than that of our other teachers,” the girl says.
The answer goes in his notebook with all of the others. “Alright. Yaoyorozu?”
“Can I build on Uraraka’s answer with my own inference?” Izuku considers this, then nods. Yaoyorozu continues, “I think that you are or have been a vigilante. It would explain why your experience and what you can teach us is different from the other teachers, and why you would keep your civilian identity a secret.”
“That’s a well-thought-out answer as well. Does anyone have an answer that hasn’t been said yet?” the only hand left up is Shinso’s at this point. Izuku makes eye contact. “Is your answer based only on what could be observed in this room, and not based on previous information? You are the only one who has figured out who I am.”
“Yes, sir,” the purple-haired boy says, and Izuku would really rather no one call him sir. It feels weird because he’s younger than some of these students. If he was still going to school, he would be in the same year as them. Oh, well.
“Go ahead, then. What have you observed?”
“You were given profiles on each of us before today. You already knew all of our names before you spoke to any of us, while most teachers take a few classes at least to learn everyone’s name,” Shinso says. He hesitates before continuing. “Am I allowed to make more than one observation, since no one else has their hands raised anymore?”
“Of course. As long as it’s all based on what you could learn from observations without prior information,” Izuku says. That is why he saved Shinso for last, after all. Shinso seems a little surprised that he answered his question verbally, and Izuku can understand why, but it’s not like any hero student would be stupid enough to use their quirk on a teacher outside of training.
“Most of your gear is homemade or can be bought from ordinary stores, indicating a lack of ability or unwillingness to buy from actual support gear providers. You probably haven’t taught before, or at least not in an actual school, because you seem slightly uncomfortable standing at the front of the classroom. You are probably unused to having a lot of attention on you in general. I think everything else I have was either based on prior knowledge or already said,” Shinso says.
“Very good. Would you like to tell everyone who I am now? Just my name, not any other information,” Izuku offers.
Shinso nods. “The Emerald Shadow.”
“Correct. Now, have any of you, other than Shinso, heard of the Emerald Shadow?” Izuku asks. A few hands go up. “Now, for those of you who have heard of the Emerald Shadow, what do you know about me? Kaminari, you haven’t spoken yet.”
“You’re a vigilante that mostly operates at night and has been active for about a year and a half,” the blond says. The answer is written down.
“That’s correct. Who has something to add? Ojiro?”
“You’re known for working with underground heroes, and even daytime heroes if they end up out at the same time as you. Most heroes, and even the police, in Musutafu are said to trust you, at least professionally,” the tailed boy says.
“Also correct. Tokoyami?” Izuku says, still writing Ojiro’s answer as he speaks.
“You operate mostly at night, got your name because you are a mad banquet of darkness when you fight, and are essentially the vigilante version of a twilight hero,” the raven-headed boy says.
“Okay, I think I understand what you’re saying,” Izuku says, writing the answer down. “Let me fill in some gaps for you all. I am a vigilante in Musutafu and have been active for a little over a year and a half. I’ve known Eraser for all but the first month of that time, and he helped me improve my skills when I was still starting out. We’ve worked together quite a bit, and I often work with other heroes active during the evening and night. I was given the name Green Shadow initially by the police and heroes when I first started getting noticed due to the color scheme of my costume and my stealth-based techniques. When I made it to the media, someone decided that Green Shadow wasn’t flashy enough and changed it to Emerald in their article, so that’s how I became commonly known about a year ago. I use stealth, observation, and analysis when I fight to even the playing field against people with combative or powerful quirks so that I can use people’s own quirks against them. Now, does anyone have any questions for me? Our time is almost up.”
“Why did you choose to become a vigilante?” Uraraka asks when she’s called on.
“I had a lot of reasons, some of which were mostly subconscious. I wanted to help people, mostly, and didn’t believe I’d be able to become a hero. I wanted to prove to all of the people who told me I’d never amount to anything that they were wrong, even though none of them know who I am,” Izuku explains. “Anyone else? Iida?”
“Should we call you Emerald Shadow-Sensei, or would you prefer something else?” the boy asks.
Izuku really hopes that the mask hides the blush on his face. “Just ‘Shadow’ is fine, it’s what most of the people I work with call me. Kaminari?”
“Will we be having more classes with you, Shadow-Sensei?” the blond asks, and that is not what Izuku meant when he said to call him Shadow.
“Yes. I agreed to lead three lessons for your class to begin with, and after that, it will be decided whether I will continue teaching here. Then I may decide that I don’t want to teach anymore, or Nedzu and Aizawa might decide not to ask me to come back, but you will have at least two more lessons with me. I suggest you all study up on observation and situational awareness before I see you next,” Izuku says, and before he can call on another student, the bell rings.
Eraser emerges from his sleeping bag. “You hellions get to lunch,” he says to the class, and they all stand to leave.
“Shinso,” Izuku says before the boy can leave the room, “could you stay behind a moment?” Eraser and the purple-haired boy both look at him strangely, but he ignores it, hopping down from the desk. Once the room is empty except for the three of them, Izuku looks at Shinso and says, “I just want to make sure you know that I always called on you last because I knew you would have the answer, and I wanted to give everyone else the chance to get some points. You never have to worry about quirk discrimination with me. Your dad wouldn’t work with me if I was a quirkist asshole.”
Shinso is silent for a long moment before he blinks. Wow, his face really doesn’t show much emotion, he must have gotten that from Eraser. “You know?”
“Yeah. He talks about you a lot,” Izuku says, smiling under his mask. “I half thought he was exaggerating your skills, parental pride and all, but you’re every bit as good as he told me.”
“He talks about you a lot too. Hell, Papa keeps asking when he’s bringing you home,” Shinso says. “I’m pretty sure he wants to adopt you.”
Eraser glares at his son. “Hizashi wants to adopt every child I connect to.”
“He was right with me,” Shinso shrugs.
“Anyway, while we’re on the subject, Hizashi is insisting that because you’re working at UA now, he has to meet you,” Eraser says. “I can take you to the staff room, or you can come over for dinner tonight. I’m pretty sure that if he doesn’t meet you today, I’ll be sleeping on the couch until he does.”
“You don’t sleep anyway,” Izuku says cheekily. “Dinner sounds good though, if only because I’m tired of takeout and instant ramen. I’m seriously starting to wish someone had taught me to cook at some point.”
“I’m sure Papa would be happy to teach you. I’m only allowed to use the kettle, the microwave, and the refrigerator in our kitchen now and Dad’s as helpless as I am, but I’m sure you’ll do better than us,” Shinso says. Izuku giggles a little.
“Does seven work for you, Problem Child?” Eraser asks.
“Yeah, sure,” Izuku says. “I’ll bring my gear so I can patrol afterward.”
“Okay, Problem Child. We’ll see you tonight. Go get some sleep,” Eraser says running a hand over Izuku’s hood in an affectionate gesture that has become familiar between them. It makes Izuku feel warm inside.
“You’re one to talk,” Izuku snarks before he leaves to do just that.
Before he’s out of hearing range he faintly hears Shinso say, “Papa’s right, isn’t he? We’re totally adopting him.”