Work Text:
1.
The first time he was introduced to the family motto, Izuku was five. He’d been diagnosed as quirkless only a few days before and his father had been home to look after him while his mother took a vacation.
He didn’t quite remember everything that happened that day, but at least he did remember why it was told to him.
He had gone on a play date with a boy quite a few years older than him, maybe 7 or 9, that his father knew. But the boy kept on calling his father, “master” and making weird comments.
After he mentioned talking to his mother about it, that was when his father introduced him.
“Izuku, I need you to do something for me,” he had said. “Sometimes, there will be things your mother can’t know about. That’s where you come in, if I give you our secret passcode, no one can know what happened that day. If you do it for me, I’ll do it for you as well. Does that make sense, Izuku?”
He had just nodded along happily to his father’s words, excited to be included in a game.
“Okay. Our password is ‘One for All and All for One, united we stand, divided we fall,’ it’s our family motto,” his father told him.
Izuku smiled and mimed locking his lips and throwing away the key.
His father ruffled his hair.
2.
The second time he remembered it happening was when he was seven and his father came home at two am smelling of smoke and blood.
He had been in the living room, watching an All Might documentary to cope with his nightmare.
So when his father walked through the door, obviously not expecting Izuku to be there, he just mimed shut lips and said the motto.
“One for All and All for One, united we stand, divided we fall.”
3.
After that, he remembered far more incidents.
Blood in his father’s shirt, the boy, who was later introduced to him as Tomura, hanging around, the strange incidents of his father seeming to have a quirk other than his fire breath.
In return for his own silence, his father granted him silence when he needed it.
Izuku could rant for hours to his father about school, about the bullying, about the borderline legal activities he got into around town (Giran and the others at the bar near his home asking for his analysis in exchange for some quick cash for Izuku).
When he needed help, with anything legal or not, his father was there.
The first time he killed someone in self defense, after puking of course, he had called his father and said the family motto. They never found the body and it was never traced back to Izuku.
Of course, while his father certainly did not approve of his desire to be a hero, he helped with that too. When Izuku wanted to train, his father set him up with sparring and gun lessons. It might not have been legal, but it certainly worked.
Izuku even got his American gun license to keep up appearances.
Their silence was guaranteed in each other's secrets and that was what made them so close.
Later on, when Izuku got One for All from All Might, he told his father everything about it.
They kept each other's secrets, plain and simple, so he had no fear of sharing. Not with his father.
He told his father how he met All Might, how he got into U.A., how Kacchan was in his class, everything about everything.
Understandably, his father was confused and seemed almost angry but given their rule, he could not act on it.
The next day after he told him about it, though, his father seemed far happier, even going as far to say under his breath, “As long as it’s back in the family” whatever that was supposed to mean.
What happened in the motto, stayed in the motto.
5.
Then the USJ happened.
Earlier that day, Izuku got a text from his father, “One for All and All for One, united we stand, divided we fall.”
If that wasn’t ominous as hell, he didn’t know what was.
So, of course, he was on edge all day waiting for his father to pull him out or do something.
With the field trip that day, which his father signed the consent form for, he really should have figured it out.
When they got to the USJ, he was immediately set on edge upon entering the building. Something didn’t quite seem right.
When Kurogiri’s portal appeared with Tomura stepping out along with the many other thugs, he wasn’t even surprised. Just resigned.
Doing his part to act normal, he fought as hard as he could against Tomura and Kurogiri. He’d apologize later, but appearances must be maintained.
He wasn’t even interviewed after the incident with the rest of his class, apparently All Might had vouched for him. Which, honestly, was good considering that he didn’t want to give away any family secrets.
6.
When Kacchan was kidnapped and he was almost beaten to death by Muscular, though, the line was drawn.
They needed an intervention.
The moment 1-A and the nurses were all out of his room, he reached for his phone and called Giran.
“I need you to break me out of my hospital room”
“ Why don’t you just ask your father or Kurogiri? ”
“They need an intervention. They went too far this time.”
“ The Bakugou brat or Muscular?”
“Both, Muscular nearly killed me and Bakugou’s rather close to home.”
Giran chuckled, “ Yeah, I’ll come pick you up kid. What’s your room number?”
“316, in the hero ward.”
“ Alright, I’ll be there in ten. Be prepared to open your window.”
“K.”
True to his word, Giran picked him up within ten minutes and took him straight to the bar.
When Izuku entered, all heads turned to him. Kacchan was chained up in the middle of the room.
“Deku? What are you doing here?” Kacchan screeched.
“I’m saving your sorry ass.”
Izuku walked up next to Kacchan and glared at Tomura, who threw him the key.
Izuku unlocked Kacchan’s chains and dragged him by his arms to just outside the door where Giran was waiting.
“Can you take him home, please?”
Giran nodded, “Sure, kid. Where should I drop him off?”
Kacchan just stood there awkwardly, watching their conversation.
“My place is fine.”
Giran started to walk off.
Izuku gently pushed Kacchan in the direction of where Giran was walking. “I’ll be fine. Just go.”
Kacchan gave him a pleading look.
He just smiled. He had to do this.
He walked back into the bar and locked the door behind him to prevent Kacchan from getting back in.
The room was completely silent. All eyes were on him.
He put his hands on his hips, “Okay, whose brilliant idea was it to kidnap Bakugou?”
Tomura slowly raised his hand, “He seemed villainous.”
“He’s the absolute opposite. Get another opinion before kidnapping someone next time. Who let Muscular on the team?”
From behind the bar counter, Kurogiri spoke up, “That would be my fault, Young Master. He seemed mostly sane at first.”
Izuku just shook his head.
“Who’s this kid?” Dabi spoke up in an annoyed tone.
Izuku cocked his head and said, “I’m One for All.”
Dabi blanched, “Sorry, sir.”
Next to Dabi, Toga whispered, “Why’d you react like that?”
“He’s one of the most influential people in the underground. The best analyst around.”
Toga was quiet.
Izuku shook his head and turned to Kurogiri. “Can I have a portal home?”
In lieu of a response, a portal appeared next to him.
He went through and collapsed into his bed. He’d get his father to fix his arms later, for now he just wanted to sleep.
+1.
The next morning, he awoke to voices in the hallway and a knocking on his bedroom door.
“Izuku, are you in there?”
He yawned and his mother opened up the door.
He sat up in bed, “Aizawa-Sensei, Mom, what’s up?”
“You have to come into the station for questioning, Problem Child. Do you know how irresponsible it was to try and save Bakugou by yourself?” Aizawa-Sensei sighed.
“It’s fine,” Izuku waved tiredly, “Dad would have stopped anything from happening…”
“Your father?”
“He’s not around much, but Izuku’s very close with his father, Hisashi,” his mother said gently.
Aizawa-Senei sighed yet again and muttered, “Problem Child and Problem Father. They’re a duo now.”
Omake 1: If Hisashi tried to talk to Izu about illegal stuff
Hisashi: “Son, I haven’t been completely honest with you. I’m All for One, the boogeyman of the underworld.”
Izuku *sighing*: I already figured that out. Why’d you tell me? Now I can’t claim plausible deniability.”
Omake 2: Why Izuku is named One for All in the underworld (Right after Omake 1)
Izuku, talking to Hisashi: “So if you’re All for One, I should be One for All. We can match!”
Hisashi, tearing up: “I’d love that.”
Omake 3: All Might confrontation
All Might: “Why didn’t you tell me that All for One is your father?”
Izuku, shrugging: “Didn’t really think it was relevant. The same way I never mentioned that I have my gun license and have an underground persona.”
All Might, in sheer confusion: “What?”