Midoriya: Wait... the last Deku chapter had Togata being attacked by a mysterious villain... or is it just the quirk... and the chapter title- oh!

Jana: Don't spoil it.

A lot of people: Uh what?

Izuku and Nezu both froze. An attack this soon after the Hosu incident? And right after they had switched to dorms as well? Even outside of the risk to the students' safety, which was obviously the most important consideration, the PR nightmare this could cause was terrifying. Nezu didn't waste any time pulling up the security feed for the third year's practice gym and Izuku quickly stood and came around the desk so he could peer at the screen over the principal's shoulder.

The scene on the screen was absolute chaos. The students were panicking and Izuku was eerily reminded of the sludge villain incident. Just like then, the heroes present weren't a good match for whatever was going on and couldn't do much except keep an eye on the writhing mess of black tendrils that was exploding from Mirio in every direction.

Wait... from?

Tamaki: Wait does that mean...

It took a second for Izuku's brain to catch up and figure out what was going on, but once it did, he was torn between giggling in relief and hitting his head against the wall, so he settled for a third option: a tired sigh that could put one of Eraser's to shame. Why couldn't All Might or Mirio have at least warned the other teachers that he might develop other powers?

Everyone: He's going to what?!

"Eraser, we're not being attacked." Izuku said calmly. "Mirio should know what's going on, just erase his quirk and ask him if you're so concerned."

"Togata does not know what's going on!" Eraser growled. "Who do you think is screaming and trying to fight back?!"

Thirteen: He doesn't know?

All Might: Well I didn't know so...

"What?" Izuku froze, this time in confusion, not fear. Had... had All Might not told him that the weird transferable quirk was a stockpiler? According to the research he'd done when he'd first tried helping Mirio with his 'quirk mutation' the quirk got stronger each time it was passed from mentor to student, which meant that it was collecting each holder's strengths, which logically included their quirks. This, of course, brought up the question of why All Might never used those quirks despite the obvious advantage those powers would give him in a fight, but Izuku had given up trying to make sense of anything that man did.

Gran Torino(pausing): ...Why did none of us think of that?

All Might: I have no idea... was this even supposed to be possible?!

Case in point, why he hadn't warned his protege that he might develop other quirks? Izuku rubbed the bridge of his nose in frustration and grumbled under his breath, "Just when I think that idiot can't do anything worse, he goes and outdoes himself. Okay, Eraser, new plan. Erase Mirio's quirk and send him straight to me."

"I know you're not stupid, Deku," Eraser was using his I can't believe I have to explain something so simple voice, "but I'm not about to erase a student's quirk when it's the only thing he can use to fight back against the mysterious villain attacking him!"

Mirio: But I'm not being attacked by a mysterious villain.

Aizawa: Other me doesn't know that.

"That is his quirk." Izuku groaned. It should not be his job to explain this. "It's a part of the mutation that... ugh, just... do you trust me?"

"Usually." Eraser responded dryly.

(everyone snorted)

"Then do what I say." Izuku ordered firmly. "Erase his quirk and send him straight to me."

"If you're wrong..."

"Then I'm already grounded, so it's not a big deal." Izuku interrupted.

(everyone snorted)

Midnight(giggling): He knows you so well Shou.

"Problem child..."

Izuku ignored the warning tone in Eraser's voice as he grabbed Nezu's phone and hung up. Aizawa would probably swear, but at least he would acknowledge that it was useless to continue the argument. Looking back to the camera footage, Izuku sighed in relief as the black tendrils disappeared and Mirio fell to the floor, visibly shaken up, but otherwise okay. Eraserhead deactivated in quirk and Izuku held his breath, waiting for Mirio's new quirk to start acting up again, but thankfully whatever had triggered it had apparently passed and it didn't manifest again as Mirio's friends ran up to him and started hugging him.

Tamaki(sighing in relief): You're okay.

Mirio: Yeah I did promise that I would be didn't I?

Izuku sighed and dragged a hand down his face before finally glancing over at Nezu, "You know exactly what's going on, don't you?"

"Ah, Midoriya, what kind of hyper-intelligent principal would I be if I didn't?" Nezu smiled. "Although I am pleasantly surprised that you figured it out as well. That's assuming, of course, that you weren't told."

Midoriya: I wasn't.

"As if All Might would ever respect me enough to tell me anything. " Izuku muttered bitterly. "I only figured it out because Mirio asked for help controlling his quirk before the school year started. Obviously, things didn't add up, but after I realized the mutations," He emphasized the excuse with finger quotes, "only occurred in a specific line of mentors and students, the rest wasn't hard to figure out."

Nezu grinned mischievously, "You'd be surprised, Midoriya. It's kept many of lesser intelligence fooled for generations. Most people never think to look, and would of course dismiss such a quirk as impossible if they ever caught a whiff of it. It takes an open mind to figure out such a secret."

Momo: ...Did he just call all of us dumb?

Manga: I think so.

Izuku blushed slightly. Even now, it was hard to take compliments like that into stride, even though he should be used to people actually respecting his abilities. So, he just avoided the subject entirely.

"Speaking of lesser intelligence," Izuku groaned and he knew that he was probably acting way too much like Eraser right now, but he was tired, "can you get All Might over here? He should really be the one to explain this to Mirio, you know? Considering that it's his fault and everything."

All Might: Except I don't even know...

Recovery Girl: And he's with Sorahiko far away.

Gran Torino: In a house with no cell service.

Endeavor: Well that's annoying.

To his surprise, that was what got a slight frown, "Well, this is an interesting predicament."

Izuku glared at him suspiciously, "What?"

"Well, All Might requested a few days off and is currently off the grid with an old mentor of his." Nezu shot him a small smile, almost like he thought the whole thing was funny. "So I suppose it's up to us to explain it then! Won't this be fun?"

Kamui: No it won't be.

Izuku was about to open his mouth and argue that no, this wasn't going to be fun and that it wasn't his job to explain anything to do with a top secret quirk that he wasn't even supposed to know about in the first place, but he was interrupted by the door to Nezu's office slamming open. Aizawa strode in, followed quickly by Mirio, who was looking more timid and scared than Izuku had ever seen him, which was what finally pulled Izuku out of his frustration. Yes, All Might was an idiot, and no, it wasn't Izuku's job to explain Mirio's new quirk to him, but he'd be @#$&* if he was going to let someone else suffer because they didn't understand their quirk, not when he could help them!

Inko: Yeah...

Aizawa activated his quirk and glared both Izuku and Nezu, neither of which gave an inch to his intimidation, "Explain. Now."

Tsukauchi: Well this is complicated.

Izuku glanced hesitantly between Nezu and Mirio, who was looking at Aizawa with barely concealed panic, and sighed. Aizawa obviously didn't know that All Might's quirk was transferable. From what Izuku had gathered, the number one hero hadn't told hardly anyone, even his successor's teachers who really should have known, but... it wasn't his secret to tell.

Toga: Except your teacher's not leaving without answers so...

"Eraser..." Izuku started slowly, but Aizawa quickly cut him off.

"No." He looked between all three of them and reactivated his quirk. "I don't know what's going on or what the three of you are trying to hide, but it stops here. Got it?"

Izuku swallowed and looked at Mirio, who smiled awkwardly and shrugged, "Uh, I don't really know what's going on either, so..."

Midoriya: Guess the secret's coming out...

Izuku sighed again and looked at Nezu, who was just grinning and waiting to see what he did, which was no help at all. He rubbed the bridge of his nose in frustration. It wasn't his secret to tell, but it would make sense for Aizawa to know and All Might obviously wasn't ever going to tell him, so...

He turned to Mirio, "We are going to be discussing the specifics of your quirk." He said heavily, hoping that Mirio would be able to understand his double meaning just from his eyes. Considering that he paled slightly, Izuku had succeeded. "Are you okay with Aizawa..."

Aizawa: I'm staying.

"I'm staying." Aizawa said firmly.

"With all due respect, Eraser, that's not... " Izuku countered.

"I'm the kid's teacher, Deku." Aizawa glared at him intensely, "So I have a right and a responsibility to know what's going on, so anyone care to explain?"

Snipe: Technically he's my student but... yeah you definitely have a right to know.

Izuku was prepared for a staring contest, even though he knew he would probably lose in the end, considering this was Eraserhead, but thankfully Nezu cut them off before their battle of wills could even really begin.

"Young Togata is beginning to develop other quirks!" Nezu chirped cheerfully.

"What?!?!" Mirio yelled in shock at the same time that Aizawa gave them both a deadpan glare.

(everyone snorted)

Recovery Girl: Really Nezu?

"Quirks mutating, I understand." Aizawa said. "But dual quirks are rare..."

"And hardly ever occur naturally, yes, I know." Izuku held up a hand to keep Aizawa quiet as he turned to Mirio again. He looked at Nezu for confirmation and when the principal nodded, just accepted it. If All Might wanted it to remain a secret, then he should have been here. It might not be Izuku's secret to share, but on the other hand, it also wasn't Izuku's responsibility to hide it. "What all has All Might told you about the past holders of your quirk?"

Mirio froze and Izuku recognized the panic welling up again as he glanced at Aizawa and gave a last ditch effort to laugh off the question, "Past holders? I, uh, I don't know what you're talking..."

Mirio: Don't worry other me, he already knows.

Izuku cut him off with a look, "Nezu already knows, I figured it out months ago, and Aizawa apparently isn't going to leave. We're all here to help you, but we can't do that if you don't let us."

Mirio stayed still for a moment before laughing awkwardly and rubbing the back of his neck, "Heh, well, I uh, I thought we were doing a pretty good job hiding it, but, uh, apparently not, so... I mean, All Might told me that I'm... I think the ninth? But, uh, I don't think he's told me anything about any of the others. He, uh, doesn't like to talk about the mentor he got One for All from, so..." He smiled sheepishly and shrugged.

Midoriya: Yeah you're the ninth.

"One for All?" Izuku asked.

"Oh," Mirio's eyes widened, "I thought you said you figured it out..."

"I literally just traced the quirk from student to teacher for nine generations and figured out it was transferable." Izuku deadpanned. "No one ever wrote down what it was called."

(everyone snorted again)

Dabi: He sounds so done with all of this.

"I guess that makes sense." Mirio laughed. "But yeah, he didn't really tell me..."

"Are you saying that All Might gave you his quirk? " Aizwa looked halfway between a blue screen and unholy rage, which Izuku found unreasonably amusing considering that that had been his exact reaction to finding out as well. "Setting aside the fact that that's even possible, what does that oaf think he's..."

Recovery Girl: Oh he wasn't thinking.

"There will be time for fighting the number one hero later, Aizawa." Nezu said with amusement. "But I believe the purpose of this conversation was to help Togata understand his little... incident earlier, not to destroy a national symbol."

Aizawa exhaled deeply through his nose and rubbed his eyes, "Fine. Deku, continue."

Izuku nudged Nezu gently so he could access the keyboard, "Well, from what I understand, All Might's quirk is a stockpiler. It takes a little bit of each holder and passes it on to the next, right?"

Gran Torino: Yes... but how did it not bring up previous quirks before?

Midoriya: Hm...

"Yeah, that's pretty much what he told me." Mirio shrugged.

"Good." Izuku swivled the computer screen so that Aizawa and Mirio could both see it. "Mirio, meet one of your predecessors. The pro hero Lariat, also known as Daigoro Banjo and the fifth holder of One for All."

Midoriya(sitting up excitedly): Of course!

Everyone(looking at him in confusion and some concern): ...Midoriya?

Midoriya(not noticing the stares): Oh that makes so much sense! My usage of One for All at a hundred percent was only around All Might's one hundred percent when he was already weakened which meant that my body was exhibiting a weaker amount of power than All Might's but shouldn't work because it's a stockpiler that should get stronger but because my bones were breaking from the strain and All Might's didn't when he got it One for All must've realized that it was hurting me and does the natural bodily compulsion to avoid using too much strength for safety and made my strength weaker and from what we saw from Togata's fight with the nomu his strength is comparable to mine which means the same rules apply and since he's got less strength the extra power had to go somewhere so One for All gave him the previous holders' quirks instead!

Inko(panicking): Izuku please just breathe! (Midoriya realized he'd been talking for too long without breathing and went red and stammered out apologies before Inko reminded him to breathe again and he stopped talking)

Aizawa: ...Seriously problem child?

Mic(blinking): That... was a lot of information.

All Might(numbly): Uh huh.

Midoriya: Yeah so other Togata should be slowly developing the previous holders' over time- (suddenly he froze and everyone looked at him even more concerned)

Shigaraki: Uh brat?

Toga: Izuku you're scaring me.

Midoriya(freaking out): Wait but if the same rules apply with me and Togata that means I'm going to develop the previous holders' quirks too!

Everyone: What?!

Bakugo(roaring): Stop being so overpowered you stupid deku!

Monoma: I hate being a side character!