AN: I don't own My hero academia

He doesn't need to know

The family had an interesting time adjusting to Izuku's new tutor. When they first saw Arata, they all thought he was some homeless man. Since then, the man had cleaned up his appearance. Handsome was a word Fuyumi used. Weirdo was a word Natsuo used. The man barely interacted with any other family member besides Izuku and Endeavour. He looked disinterested if he was around any of the other children. When Rei tried to approach him, the man brushed her aside. He was focus on one thing and one thing only. That was Izuku's academic development. Making personal connections outside of his boss and student was unnecessary. Or at least that how he acted.

One day Izuku asked to take some extra lessons on the weekend. Since the boy was so insisting, Endeavour agreed but only for one extra day every other week. Arata agreed with the terms and that's how it came to this scene: Natsuo and Fuyumi stared at their little brother's door. They were a little worried with how much their little brother has dived into studying. It was already bad enough they rarely see their eldest with all the training he does. Now the same thing was happening to Izuku. Both agreed it was unfair. Izuku was too young to study this hard. The difference was they couldn't completely blame their dad like what they do for Touya. Izuku wanted this.

"What do you think they're doing in there?"

Fuyumi pressed and ear at the door, "shhh! I'm trying to hear." The plan was to catch Izuku as soon as his break started and do something. Anything other than having that boy's head shoved in a book for several hours. They even got a ball…although they couldn't use it with Izuku. Not when their father doesn't allow it. That didn't matter much. What did is to get Izuku to be a little kid. Laugh and play as much as they used to.

Meanwhile, on the other side of the door.

"And that is why hygiene is so important in any industry but especially medical. I can go into deeper science, but you are a little young for that. It can get a quite gruesome." Arata concluded while shutting a book about medicine in his hands. As Arata promised he stared to introduce other professions Izuku may want to consider with a heroic element to them. He started off with something obvious that even heroes needed. Those in the medical profession. He could tell the child interests was high but not high enough for him to be sold on the idea yet. Perhaps something else.

Izuku frantically wrote down notes. From what he understood the stuff he was learning was an overly simplified vision of what he would need to know. It was hard but he was slowly getting his head around it thanks to Arata's thorough and patient teaching. Then the boy raised his hand, "I can I make a request?"

"You may."

"Can you teach me how to treat burns better?"

Arata was caught off guard by the sudden request. "Burns? That's oddly specific. I could if that's what you want to learn. I'll need to do some of my own research first."

That got Izuku curious. "You don't know?" You'd think as a teacher he would know everything. He sure acted like that in class time.

Cheekily, the tutor winked. "Even teachers need to learn." His eyes then darted to the door. Those two were being awfully noisy. It was distracting. Then again this presented an opportunity. "Izuku, you've been working so hard. Why don't you go play with your siblings?" His eyes glowed along with the door. Without warning it slid open. The sibling pair, who were both leaning against it, fell inside with a thud. They both groaned while Izuku yelled if they were ok. Arata on the other hand just chuckled. "They seem eager to play with you."

His two siblings laughed nervously while standing up and apologising. "Sorry to interrupt."

"No, no, your timing is actually quite perfect." Izuku's body began to glow before he was transferred safely to his siblings. The man's smile was everlasting while he stared down at the young children. "I need to reorganise Izuku's lesson plan a bit. As you both say Izuku has been working very hard. A small break would be advised. So why don't you three play ball like you wanted."

The two looked at each other confused. They didn't remember saying anything like that aloud. Especially the play ball part. Did they? Soon Izuku interpreted with a sadden tone, "I'm not allowed to play ball." That was an odd thing for the tutor to hear. Why would a child be denied playing a simple game? "Father doesn't like it when I get hurt. So, he doesn't let me play roughly." Even his siblings behind him looked disheartened while their sad longing gazes shot at the ball.

Silently, the man stared at the children. How odd. He didn't expect a man like Endeavour to be the extremely overprotective type. As a man that values strength it made more sense that he would want his children to be the same. Yet he seemed only hyper focus on two. His eldest and his youngest for two completely different reasons. He shrugged the thoughts off as unimportant. What the other family members do was none of his business. His only concern was Izuku's development. Although, Endeavour hampering of Izuku's freedom could threaten that development. Arata could clearly see the amount of doubt the child had in himself. It wasn't a stretch for him to believe it was due to his father's productive habits and demands. The fact the boy seemed willing to go along with it was also a hurdle. There was a way around it. The grin the man worn grew dark with mischief. "You know. What Endeavour doesn't know won't hurt him. He doesn't need to know anything about this."

The children perked up at the sudden suggestion. It felt weird hearing that from an adult.

Arata brought a finger to his lips and winked. "I won't tell him if you won't. So why not play awhile since he's busy. I'll even lend a hand so you three can play in peace."

The older siblings' eyes glistened as they two tried to convince their youngest brother to go along with it. Mainly, Nastuo. Their father would be busy with Touya for the next couple of hours or so. That would be plenty to time play and no one will know but them. Father won't get mad, and they'll have fun. Even so, Izuku wasn't convinced. "If father finds out, Natsuo and Fuyumi will get into a lot of trouble. Besides it's for…my safety."

Then Arata knelt to the children's eye level still smiling. Facing Izuku, he lifted his hand sideways and smacked the boy's forehead with it. His older sibling instantly jumped into action pulling Izuku away from the man. Using their bodies as a shield, they held Izuku back. They yelled at the so-called teacher demanding what he was thinking.

Innocently, he lifted his both arms up as if he were surrendering. "You didn't break," Arata stated simply. The children glanced at each other confused. This man has a few screws lose; they were sure. "Just because you're quirkless doesn't mean you're delicate," he continued. There was this fondness in his tone when he said the word 'quirkless'. Like the word meant something dear to him. He placed a hand over his chest and cupped something. The children weren't sure what it was. "It's a misconception many have that quirkless need constant protection or else they'll break. In reality, they can be just as strong as anyone with a quirk. Some even stronger." He then stood up straight. The ball that was tossed aside by the siblings in favour of their little brother floated to Arata's hand. "You're able to stay standing after getting hit. I'm sure you can survive a ball." He then threw the ball at the children. Izuku easily caught it. Like his teacher said he was still standing. "Have a little faith in yourself, Izuku. Beside you have two great older siblings to look after you. You'll be fine."

Izuku stated at the ball contemplating his options. He was standing. His siblings will be there too. If his father never finds out no one would get into trouble. He looked up at his siblings. "Can I play with you guys?"

"Well dun," Natsuo grinned while slapping Izuku on the back. "None of us will tell dad, right?"

Fuyumi nodded along. She felt a little guilty going against her father orders, but it was just a game of catch. It's not like they were doing anything criminal or dangerous. "Ok but let's stay quiet." She gazed up at the teacher still a little worried. "You won't tell anyone right, Mr Darewell?"

"I won't, and please call me Arata," he corrected.

Natsuo playfully punched the man at his side. "You know for a weirdo. You're pretty cool Mr Arata. Now let's play." The three of them hushed themselves and happily ran out.

Arata casually followed the excitable children. Someone needed to keep watch for the big fire man. His eyes gazed at the direction his boss currently was. He could hear them. The grunts and roars of intense combat suddenly halted to a stop. He could also hear other things. The kind of voices many don't dare to say out loud. Some of the things he heard were concerning. Then again it wasn't any of his business. Although the things he heard were interesting. He hummed in thought. "So that's why he wanted to learn about treating burns. You're quite the thoughtful child, Izuku."

Then a pair of footsteps travelled around the corner. Stumbling through was young Touya. His arms banged up much more than usual. His eyes were covered in his bangs. They were newly painted with white. The boy kept his head down while he bit his lip frustrated. You could feel the heat of frustrated rage pouring out from him. It felt like leaving a heater on too long that it might burn out. The boy said nothing to the man as he walked pasted him like they weren't there. The thoughts storming in his head were vicious.

Humming, Arata spoke to himself. "Shall I act?" He thought about it more and dismissed it. "That is not in my jurisdiction. My interference may only complicate things. That would be bothersome." Then his hand unconsciously travelled to his chest. Hidden behind his shirt was a precious item. He touched his smooth hard shell beneath his shirt. It gave him comfort. "You would disagree with me. Won't you?" He looked back to where the angry child walked off. His mouth open but it shut a second later when he heard a new voice.

"Touya? Is your training today finished?" It was the lady of the house Rei. Arata didn't talk to her much for many reasons. One of which was that he simply didn't care much for her. It was something about her that didn't sit well with him. He shut his mouth and decided to remain in the observer role. There was worry in her grey eyes as she attempted to touch her son. "Your bandages…You got burned again."

The boy clicked his tongue at the obvious statement. It's been like this for years so it shouldn't be surprising anymore. Harshly, he smacked her hand away. "Dad let me out earlier for a break but I'm fine. I just need to cool off a bit." His bitter gaze shot at the woman. The dragger like stare caused her to flinch as if she did get cut. "Why do you care? This was the whole reason why I was born right? So just back off. You don't need to make or take any kids again. I'm the only one who needs to do this."

Rei gasped and lost her voice. Her heart sank to her stomach while her eyes fell heavy with guilty. Their family was never founded organically. It was more of a business deal. That didn't mean it hurt her any less. To hear those words form her own child was like a knife through the heart. Arata remained silent through the exchange. Listening and thinking. The two of them seemed completely unaware of him. The longer he watched the more he affirmed with himself it's not his place to interfere. He was ready to turn his back again.

"Arata sensei?" The man's eyes shot at the voice calling to him. Izuku stood there with a wondering expression. "You weren't following us anymore. Aren't you coming?" The child's voice altered the others to them. Arata looked over to the mother and son and Izuku's gaze followed his. The child's eyes widen as if he completely understood the situation. Worried, he trotted up to his mother and elder brother. "Are you two fighting again?"

The two Todorokis said nothing. Only gave each other silent glances.

It was enough of a tell for Izuku. "No fighting!" He cried. The child rushed up to his brother and crashed into his chest. His little hands gripped at his shirt while tear drops formed around his eyes. "I'm fine now so don't fight with mom anymore," he begged. It was then he noticed his brother's bandages. His eyes sadden further. "You're hurt again." His little hand ghosted over the fresh bandages. There was more. It made the boy want to cry more.

Soon Touya's bitter expression melted away to a gentle smile. He held his younger brother tightly and wiped his tears away. "I'm fine Izuku. So don't worry about me." He assured while stroking the boy's curls back. It was almost like a switch was flicked and the boy become a good, loving brother. "How was your day today?"

"Arata sensei had been teaching me about germs and other stuff. Do you know there are these germs in our stomach that help us stay heathy?"

"Are there now?"

Izuku's teary eyes glowed with excitement. He bounced at his knees happily while rambling on about all the things he'd learned today: about the human body, different organs and their purposes, Bacteria and such. Anything that he could remember. Which was a lot. Touya happily listened to it all. Nodding at every other fact his little brother told him. There was a part of his mind that wondered if the boy was supposed to learn this stuff so young. Shouldn't be learning about simple things like adding and how to read. At least they were happy.

While the two children talked, they left their mother completely isolated. She simply wasn't there in their world. It became more apparent with each passing day. A shadow casted over her expression while he lips thinned. Arata watched the woman carefully. A cold air was forming around her. Then he heard them. Those dark voices. His eyes dilated sharply as the woman walked away. It was clear she wasn't needed nor wanted there.

Then new voices came. "Hey, what's taking you so long!" Popping in form the garden was Natsuo and Fuyumi. Once they noticed their elder brother and rushed over to him.

"So that's what was taking so long. Father let you out early, Touya? You want to play?" Fuyumi asked excitedly while holding out the ball.

Touya raised an eyebrow. "Didn't dad banned Izuku from playing ball?"

Natsuo jumped into the boy's face with a finger between his lips. "Shhh! Dad doesn't need to know anything. So don't go telling ok. Or else."

Laughing at the hollow threat, Touya smiled. It was good to see his siblings so energetic again. The house has been gloomy lately after Izuku's last doctor's visit and all the restrictions their father was putting on him. Things feel a little more normal when his siblings act like this. "I won't tell if you guys won't." He promised. Then he felt someone tug at his shirt.

It was little Izuku with a hopeful pair of eyes. "Will you play too, Touya?"

Sadly, the boy shook his head. "I still have some training to do. So have fun, guys."

"Are you sure? You look tired."

Touya nodded. His eyes looked hallow for a second. "I'm fine," he reinstated and turned away.

Arata took one glanced at the boy's back as it slowly grew smaller by the distance. He hummed in thought and dismissed them all. He then turned his attention to the disappointed children. Smiling, Arata patted the Izuku's head. "Why don't you lot go play? There is just one thing I need to take care of, however. So run along without me. I'll be with you in time." The children nodded and trotted off to the garden. He kept his wide smile on as long as he needed to. Once the children were gone the smile disappeared. Replaced with a cold thin lips and sharp expression. The glared down to the direction the woman left. She was something he couldn't ignore.

Rei was in the kitchen boiling herself a kettle. Tea seemed to be the only thing able to calm her throbbing mind. It just rattled with thoughts. Scenarios that only the darkest parts of hearts wished. She doesn't know what to make of her family anymore. Were the steps she made right? Or were they mistakes? The boy she took to replace her own was more than odd. A quirkless, useless child and yet her husband still cared for him. Why? What was the point? He only ever wanted strong children. That was the whole reason for their marriage. Yet he showed the most affection towards the weakest. It was unfair. Touya was the strongest. The boy was what he wanted. Yet the brutality he causes to the child's body is ignored. One scratched Izuku gets, and he gets bandaged head to toe and forced down to rest.

Would he be like that to their real child if she never made the swap? All the route led to no. That child had the highest possibility to be Endeavour's so call 'perfect creation'. Therefore, they would have been treated worse than Touya if she kept him. Then Touya would be tossed aside without a sound that. She couldn't begin to imagine what could happen then. They were better off with a different family. She hated. Izuku was different. An anomaly she introduced in this family that somehow manged to change it in ways she would have never believed. She still doesn't know what to think of it. While her husband has calmed over the years, he was yet to look at Natsuo or Fuyumi. Touya wounds are harder for her to accept as just training. The burns he gets…she began to wonder. How would Izuku feel if he gets burns like her son. The thoughts grew to a sick desire. Her mind was wondering.

She was so distracted she didn't her and sense the man stepping closer to her. Each step coldly tapped on the hard floor. He leaned closer until his mouth was right next to the woman's ear. "Those are some unsightly thoughts you have there, miss Todoroki."

Rei instantly jumped along with her heart. She stumbled away from eth man. She would have completely fallen if her arm didn't grab on to the counter in time. "Mr Darewell. I didn't see you there. Do you need anything?"

Arata ignored the question. Instead, he decided to make himself a cup of tea since he was there, and everything was provided. The lack of a response made Rei anxious. it was like she was caught doing something bad. The man's never-ending smile made the whole scene that more uncomfortable. Once the cup was made, he took a sip. His eyes shot back to the woman warningly. "I do hope you don't act on those thoughts. I would have to interfere then."

"What…what does that mean?" She asked.

Again, Arata ignored her in favour of his tea. His eyes grew cold and sharp while there raked across the woman's frame. Her mind was in a frenzy. It was a headache to listen to. Finally, he put the cup down and glared down at the woman. "Consider this your first and final warning. That boy you dislike so much is my student. As his teacher I have a duty to ensure his development is both efficient and safe. Anything in the way of that development..."

Suddenly, the air was taken out of Rei's lugs. It was like there was a rope around her throat. Tightening ever so slightly to the point of suffocation. She scratched at her neck, but nothing was there. Some invisible l force was keeping her up and there was no escape.

Smiling, Arata said his final haunting words. "They will be taken care of."

The invisible force was gone as suddenly as it appeared. Rei slumped over the counter trying to get her breath back. Her heart was racing a mile a minute. It's been a long time she felt anything like this. Not since she first met her husband. Complete and utter fear. Her eyes darted back to the man. He was still smiling despite what had transpired as if it never happened. It was far from unsettling. It was terrifying.

"I'm glad you understand," he said all too cheerily. "Now then I should go. The children are playing ball outside and before you mention your husband don't worry. I'll be sure he never knows about it. Children their age should have fun playing games together." With that said he walked away while humming a cheery tune.

AN: This was another odd one I'm not too sure of. But it had to happen. Mainly Arata's general place in the Todoroki family dynamic and his feelings towards the other family members. Also planting the seeds of the far future. This man will be both the worst a best influence in Izuku's life.

Dreamer-Sara – I can see why you thought of Aizawa. Arata was pretty depress at the start and a mess. Glad you like him so far.

Knightwalker405 - …let's just say it's very personal.

Alpha Therapy – for sure if Endeavour wasn't a jerk, he could be number 1. I say could because this is All Might we're talking about. What's been holding him back is public opinion which is poor. Anyway, hope you'll like Arata. He'll be sticking around for a while. He may be that friend Endeavour needs…then again, he currently doesn't give a damn about him. Or anyone in the family. Izuku is his one and only priority.

Liziliza – glad you like Arata so far. He will be an interesting addition and will certainly not treat Izuku like glass. We'll see what Izuku will decide.

Harleking31 – well I update this at least once a week since they've much shorter than my usual. I won't say whether you're right or wrong. Also, Shoto is on the list. Just very far down. There's a lot of stuff to get to before him officially.

Guest – I assure you he's not.

Fencer29 – I thought I recognised your name. Also, I don't blame you I haven't completely dived into Arata besides many little hints of his other faces. Unfortunately, I don't think I'll ever be able to tell Arata's complete original story. I do have something close to it in this AU. But yes, the swords will make a comeback. They just have a different target. Also, yeah. I tired looking but the possibilities were few. The ones I could make work required a lot of reworking of the cannon timeline and future cannon events. It would have been a too complicated and things are already complicated with the season 2 event list. I will be messing with cannon a lot.

Middernacht – as much as I love detective Izuku that is not the endgame route. I felt it was too independent of a job for Izuku's main goal which is to be useful for his family. Although I might have an event where he acts like one.

A friendly dude – thanks and I'll chose week since next month is going to be a juggling act. Though I think I'll be able to keep with my schedule for this.

And that's all. Next time they realise Izuku has quite the eye.