In response to Infinite Khaos, if he'd arbitrarily swapped bodies with All for One or taken over at an earlier point, instead of an open venue where the entire world was watching, all that the OC/SI would accomplished is placing a target on his back that he couldn't get out from underneath.
In Marvel Comics when Dr. Doom pulled a "Superior Spider-Man" on Tony Stark and tried another of his world domination plots in someone else's shoes, Tony didn't take his own body back when he could've because Dr. Doom irreparably damaged "Tony's" reputation. Also, in the context of this universe, as we're about to find out, it was a "crime of opportunity", and there's another very good reason why he didn't seek All for One out and use [Body Change] on him.

thenewprime721: HE HAS FUCKIN CAPTAIN GINYU'S ABILITY! Dude, that was such a deep cut to my childhood.

Re: I'm a high-functioning autistic, so sometimes when ideas come to me, they come out of my hindbrain. If I weren't autistic, if I were quote/unquote "normal" like everyone else, I don't think I'd have been able to come up with it in the same way because my brain would be wired completely differently. Some of my best ideas, I think, only come to me because of my autism.
And that's why I came up with the idea to combine My Hero Academia with elements of So I'm a Spider, So What? with traces of Dragonball Z and the Isekai sub-genre I sometimes-love, sometimes-hate.

TM11: Love the idea! I never thought of using Captain Ginyu's technique as a Quirk. That's a genius idea.

Re: It's an interesting idea, sure, but unless you use it on a Bad Guy in front of everyone, with a damn good reason (like being pinned under rubble and about to die) you'll face a worst stigma than Shinso or Izuku for their respective Quirk or non-Quirk respectively. Its why I wrote this as a Narrative Experiment, and as I pen this Reply, a favorite line from CodeGeass comes to mind.
"When there is evil in this world that justice cannot defeat, would you taint your hands with evil to defeat evil? Or would you remain steadfast and righteous even if it means surrendering to evil?"
In either case, evil remains, but in "Office Man's" case, he's replaced the "Symbol of Evil" with his own kind of "evil".

As for Soup's comment, I promise only to try and not let this theme overstay its welcome.
MOST of my stories are long-form, as in series-spanning, but I'm trying to get into more "Localized" stories that are more self-contained and get to the "payoff" sooner instead of trundling along "at a glacial pace". This is one such example, but I have another MHA self-contained story in the works.

*SIAFO,SW?*

*Cough*

"Uuugh… Holy fuck, am I still alive?"

All for One's body shifting from its waking position, found itself tied up in a straight jacket and strapped down to an uncomfortable metal chair.

"Um… Helloooo. Guy who's blind as fuck over here!"

The Symbol of Evil, who had bandied words with one of the Kamino Nightmare's victims before getting caught up in his Quirk before mysteriously falling lifeless, shouted out through the breathing mask affixed to his face.

The sudden movement immediately awakening the guards of Tartarus to his awoken status, triggered the chain of events that had been pre-set upon his capture, which in of itself had occurred under mysterious circumstances.

*SIAFO,SW?*

"And you're sure of what you saw?" Naomasa Tsukauchi, otherwise known as 'True Man', inquired of the man who was walking down Tartarus' halls beside him.

"As sure as I can be with my own eyes," Toshinori Yagi, formerly the No.1 Hero, The Symbol of Peace: All Might, replied.

He was clad in his "Golden Age" costume, though it ill-fit his now-emaciated frame. Because the fight in Kamino Ward had concluded so-early, he still had some lingering embers of [One for All] left within him by its conclusion.

Following All for One's capture, he'd held off on using what little of his Quirk remained in case the entire thing was a convoluted ruse; no matter how-many people there were in Kamino Ward that he could've saved. He'd waited for three days before the man in question had awoken, and by now, those embers had all but extinguished.

By the morrow, the only one that carried the torch of [One for All] would be his successor.

"Do we have any information on the guy that… 'body-swapped' with All for One?"

"If you mean his body," Naomasa said drawing a sheaf of paper from his coat. "Name: Kenji Sato. Age: 25. Occupation: System Engineer. Quirk: None, but that last one's obviously a discrepancy. X-Rays can be easily faked."

"Well, obviously if you had a Quirk like that, you'd rather be 'Quirkless'," All Might admitted. Hitoshi Shinso of the General Course had a Quirk that most would consider 'villainous', and it had given him a bit of a complex crafted by a world where power meant everything. Neito Monoma had a Quirk that could copy other Quirks, and it'd given him his own sort of complex crafted by a world where individuality meant power. Izuku Midoriya had no power of his own until it had been passed on to him, and in a world where one's individual power was justice, weakness in of itself was considered a crime.

With the first of many such sad stories in mind, Toshinori could only begin to imagine what sort of hell Kenji would've had to endure, had he advertised what Quirk he had even if he never used it for malicious intent.

But that just raised the question; if his Quirk was body-swapping, was All for One the man's first victim, or his latest…?

"We backtracked his history, though there doesn't seem to be anything to imply that someone else might've moved in and shifted the furniture around," Naomasa spoke up. "Of course, that's why I'm here. To ascertain what's true, and what's false."

"Indeed. If this is Kenji's first usage of his hidden Quirk, though it's complicated, we might have to let him off the hook in some capacity. We can't in clear conscience imprison an innocent man for All for One's crimes, nor can we imprison him for Improper Quirk Use since his life was in danger," All Might nodded. "However, if 'Kenji' is simply another victim…"

"We're here," Naomasa interrupted, the two of them standing before the ultra-max security bunker/cell at the very bottom of Tartarus. A cell that had been specially-engineered just for All for One more than a century ago. Back when knowledge of his existence was common and had not yet faded into myth and folklore.

*SIAFO,SW?*

"Hello?" the body of All for One spoke up, scarred-over eye sockets rising as the cell's bulkhead doors whooshed open. "Is someone there?"

"Mr. Sato? This is All Might," the man spoke to the back of his former nemesis, the seat turned in the opposite direction as a precaution to avoid any further body-swapping. This modification had been done on the assumption that it was directional, or even line-of-sight; though would he even be able to jump ship without working eye sockets?

Thoughts for another day.

"Ah, All Might. Glad to see you're still kicking. My friends call me 'Kenji'; or at least they would if I ever had any," All for One(?) replied bitterly. A tone that the former No.1 Hero and Police Detective recognized from many embittered persons their superhuman society created.

Though he kept this opinion to himself, back when he had been Quirkless and even up until now, it seemed that as soon as the word "Quirk" came up in conversation, everyone in the vicinity became dumber than a herring sandwich.

"Be that as it may…" All Might said looking over to Naomasa, the man shaking his head to imply that the man hadn't told a falsehood that would've triggered his Quirk. "We would like to ask you some questions."

"Go ahead. Not like I'm going anywhere," the man said shifting in his strap-down seat, the gun turrets on the walls shifting in response to his movements, though All for One(?) didn't notice, or didn't care.

"What is your name?" All Might began.

"Kenji Sato."

"How old are you?"

"25. I turn 26 on the sixth of December."

"What is your Quirk?"

"I'm not sure if it is a Quirk, but I know I have the ability to switch bodies like Captain Ginyu."

At this, Naomasa blinked confusedly, but shook his head. Nothing in that statement had proven false, but that in of itself raised more questions.

"What do you mean you aren't sure it's a Quirk? What else could it be?" All Might inquired.

"Do you have someone with you with a truth-detecting or some kind of compulsion Quirk?" Kenji inquired in turn. "Because the answer to that question is probably more-ridiculous than All for One looked in my body when I stole his."

"Oh, uh, where are my manners. This is Detective Naomasa Tsukauchi, from the Tokyo Police Force," All Might answered realizing his lapse. "I trust his judgment implicitly. If he says you're not lying, you aren't lying."

" . . . I'll take your word for it," All for One(?)/Kenji said after a pause.

"What's that supposed to mean?"

"I mean, anyone can say they have this or that Quirk. You get enough people to believe you at the start, and suddenly your word is gospel."

"Who watches the watchmen," Naomasa returned.

Despite his reputation, there were always those that were skeptical about the authenticity of his Quirk, which was a perfectly valid concern to have. There had been many charlatans in the past who claimed they had a truth-detecting Quirk, and they either did have the Quirk and they lied about their results for a pay-off at one or more points in their careers, or they never had it in the first place and were just leading everyone around by the nose with charisma alone and a few lucky breaks.

It was why the assertions of such "Truth Tellers" were always backed up by evidence. In the best of circumstances, at least.

" . . . You know, I wouldn't have believed that All Might were actually some kinda sun-dried tomato if I hadn't seen it with my own eyes. Back when I had eyes," All for One(?)/Kenji replied.

"If you could answer my previous question; what do you mean you aren't sure your ability, [Body Swap], is or isn't a Quirk?" All Might repeated, using the placeholder name he and Naomasa had agreed upon.

" . . . I died before what happened in Kamino Ward. And I don't mean I got into a bind and jumped ship to the next sap that got in front of me years ago. I mean that I died in another world and reincarnated into this one like that done-to-death sub-genre of light novels and manga."

All Might blinked, turning to Naomasa who slowly shook his head. The man before them wasn't lying, and Naomasa looked as utterly stupefied as All Might felt.

"Are you trying to tell me that your Quirk is actually some sort of… 'Cheat Ability' you got from some sort of deity?" All Might inquired, having read some of the 'Other World' genre before he'd met his mentor.

By and large, the Isekai sub-genre was the go-to for anyone in need of some form of escapism; which was either the Quirkless minority or those with 'Junk Quirks' that you couldn't use to become a Hero. Which, uniroincally, were the ones that most Isekai pandered to; a Quirkless person getting a power and using their "future knowledge" to benefit whatever faction they were part of, or someone with a "Junk Quirk" becoming "The World's Strongest".

"That's how I remember it," All for One(?)/Kenji replied. "I lived my life in another world, died in some sort of accident, and I met God. For some reason he looked and sounded like Keanu Reeves instead of Morgan Freeman, who I always thought God would've looked like; but that was influenced by Bruce Almighty and then Evan Almighty after that."

"And this… 'Captain Ginyu' person?"

"This world also had Dragon Ball Z back in the late 1980s, so I'm sure you can pull it up on the wiki."

" . . . "

*SIAFO,SW?*

Since procedure dictated that no-one in Tartarus be told anything about the outside world, ever, both All Might and Naomasa stepped out of the room, down the hall past the bulkheads, and went to a wall terminal next to the elevator. After getting in touch with security upstairs and making their request, they learned that there was in fact a manga called Dragon Ball Z back in the 1980s, about two decades before the first Quirk manifested, and more than two centuries back at-present.

A further inquiry into the name "Captain Ginyu" told the story. Captain Ginyu's signature technique, [Body Change], did exactly as what had happened between Kenji and All for One, down to the lightshow and mouth-leaping lasers.

This of course raised more questions than it solved for, so they returned to All for One's(?) cell and resumed their questioning.

*SIAFO,SW?*

"I'm sure you can understand how-ludicrous this all sounds," All Might returned, not relaying that according to Naomasa, Kenji was telling the truth.

"Why would it be ludicrous? This world is exactly the sort of place someone would 'reincarnate' into."

"What do you mean?" Naomasa asked.

"When I grew up again in this world, I quickly learned that this world had the holy trinity of marginalized people commonly found in the Isekai sub-genre," the man bound before them replied. "You have the people who didn't get some kind of magical power in a world where the majority had magical powers and everyone based their self-worth on it. You have the 'non-humans' in a world where physical appearances mean everything no matter who says otherwise. And then you have the people with the 'evil powers' that get you ostracized before they've even done anything. The only difference is Quirks are a product of science and not magic. Or at the very least that you can quantify them using science and no-one knows they actually are magic, if they actually are."

" . . . And could you explain why you chose Captain Ginyu's signature ability?" All Might inquired, warily.

"I didn't choose. It was by chance," the man before them replied. "When God offered to send me to another world, he offered me a quote/unquote "Cheat Ability" at random. First I drew lots from a box concerning where my Cheat Ability would come from. The lot came out as Dragon Ball Z by Akira Toriyama. After that I drew names, and I got Captain Ginyu. After that, I had a choice to make; I could either forfeit all of my memories but keep the knowledge I possessed about this world beforehand in the form of 'foresight', or I could forfeit all of my meta-knowledge of the world I was reincarnating into and keep my original memories."

"What do you mean 'meta knowledge' of this world?" All Might demanded.

"As I just explained, I had to make a choice. Since giving up my memories would be little different from actually dying-dying, like in Black Summoner, I chose to hold onto those memories in exchange for everything I might've known about this place. That means, I don't know what the media this world is based on would've been called back in my world, whether it was a manga, a light novel, a video game, a tabletop game, or all of the above, let alone the course of past and/or future events."

All Might turned to Naomasa, the man shaking his head. No lies.

Though by the way he was alternating between rubbing his forehead, his temples, and the bridge of his nose, this whole thing was giving him a migraine for a reason other than his Quirk.

"If you hadn't made that comparison about marginalized people in the Isekai sub-genre, I wouldn't have believed any of this."

"Can't your friend tell if I'm lying?"

"He can, but that either means you aren't lying, or you just think you aren't lying."

"Like memory alteration?"

"As such," All Might replied. "We'll have to screen you through multiple parties and corroborate their findings, of course, but we obviously can't leave you here if you aren't All for One."

"Oh? So you aren't just going to bury this? Tell the 'noble lie' that you defeated the Supervillain from all the old wives' tales?"

"No! I would never allow it!" All Might demanded as he shot up from his seat. "An innocent man should never be made to pay for a crime he didn't commit! No matter the circumstances!"

"Apart from lying about having a meta-ability and then using it, you mean?"

"Those were extenuating circumstances. Since this is allegedly the first time you used an un-registered meta-ability, you're bound to get some leniency. All for One was also an SS-Rank Villain who was directly threatening your life after threatening countless others in Kamino Ward, and it isn't… uncommon, for people with 'villainous Quirks' to pretend to be Quirkless," the former Symbol of Peace admitted, loath as he was.

"So you're saying I might actually see the light of day gain? Figuratively speaking, obviously."

"You have All for One's body and his stolen Quirks. Can't you use those to see?" All Might asked, withholding a chuckle at the irony of it all.

The man had been stealing Quirks for centuries, and the one who ultimately defeated him was someone who had stolen his Quirk.

Kenji Sato had of course also stolen the man's body before his old one expired, but that was semantics.

"And how would I know how to use these Quirks? I only ever had the one ability, and it was a fire-and-forget. Captain Ginyu might've had Goku's body for a time on Namek, but he couldn't use the man's techniques and his Power Level fell because it wasn't his body."

"That's… a perfectly valid explanation," All Might hummed, remembering that what had made All for One so-terrifying was his longevity, and all the time he'd invested into learning how to use Quirks of all kinds.

In most cases, it took a person's entire lifetime to master only one Quirk. A part of what made [All for One] so terrifying, was that the user could stockpile many Quirks, and as William Shakespeare once said- "A jack of all trades is a master of none, but oftentimes better than a master of one."

Kenji Sato was only in his mid-20s, if you excluded the life he had before "reincarnating", and he hadn't had any other ability apart from [Body Change]. Of course he wouldn't automatically be able to use All for One's original and stolen Quirks.

Which also went a long ways to explain why he hadn't body-swapped before as opposed to spending his life as one of the marginalized "powerless". Not only would he have not gotten the fore-knowledge of how to use the Quirk of whatever body he stole, but he also wouldn't have any of its component memories. That meant no anniversaries, no passwords, no pin numbers; nothing.

That Kenji had the restraint not to use [Body Change] for personal gain spoke great volumes about his willpower and moral fortitude.

Or at least it would after the man's next question.

"If you had a secret power that would've let you switch bodies whenever you wanted to, why didn't you?"

"Like I explained before, using [Body Change] wouldn't automatically give me control of whatever Quirk the guy or girl I would've swapped with had. Not only that, but if their friends were observant-enough and the person I had swapped with managed to get away in my body and let it get around that someone used a 'body-swapping Quirk' on them, as crazy as that would've sounded, any idiot could've put two and two together. And on top of all that, I didn't body-swap with anyone because it would've been wrong. If I'd kept any sort of fore-knowledge about this world but gave up my original memories, there's no telling how much damage 'the new guy' would've caused in my stead. That's why I chose to keep my original memories but gave up anything I might've known about this place, if I even knew anything about this place to begin with. 'Had to be me. Someone else might've gotten it wrong.'"

"Who said that?" All Might asked, recognizing it as a quotation instead of a declaration.

"Mordin Solus. An alien who said that before giving his life for a cause he believed in."

"Oh? What genre?" he asked, finding the perspective of someone who might've "reincarnated" quite interesting.

Outside of his teaching, he might have to brush up on hold hobbies again.

It wasn't like there would be any shortage of free time outside his work, now that his time as a Hero had ended.

"A sci-fi game that played like a space opera."

"Hm. Neat," All Might hummed, realizing once again that the man before him was nothing like All for One. Nothing in his countenance, or his expression.

He truly felt that this wasn't All for One, but instead one of the man's final victims who had played the Symbol of Evil for a complete sucker.

"Do you resent me for what I did?" the man before him asked. "Beating the bad guy when you couldn't?"

All Might was tempted to say he had beaten All for One before… but swiftly realized how foolish that would've sounded given All for One hadn't stayed dead.

Technically speaking, that "final battle" had only counted as a "win" purely within his own conscious. In reality, it had been a draw, though some would argue that because All for One had been able to slink away, lick his wounds, and try again, that it had ultimately been a loss for the so-called Symbol of Peace.

"Whether it was me or someone else who bested him, either way I would've won. In principle, at least," All Might replied.

"There's another quote I'm really fond of," All for One(?)/Kenji stated. "When there is evil in this world that justice cannot defeat, would you taint your hands with evil to defeat evil? Or would you remain steadfast and righteous even if it means surrendering to evil?"

All Might felt this hit close to home. He always espoused on television that murder was never the answer, that there was always a chance that a Villainc ould be redeemed and allowed to return to polite society. However, at the first opportunity, he'd turned around and legitimately attempted to murder All for One with his own two hands. And for a long time he'd been proud that he had allegedly succeeded.

"In either case, evil does not end. The ideal situation would be to choose the option that prevents more evil. In this case, one side loses while the other wins," All Might found himself admitting.

"I guess if I'm put on trial for using such an 'evil Quirk', I could always use that line as part of my defense; get the philosophers up in things and divide the jury," the reincarnated(?) man chuckled.

" . . . That's all for now. Just stay where you are, and we'll talk to you soon."

"Not like I actually can go anywhere. And what the hell is that noise?" Kenji asked looking around, the turrets following his every movement, but not yet firing.

"Um. Don't worry about it," All Might replied, deflecting the question like he had when people asked what his Quirk was.

*SIAFO,SW?*

"You have got to be joking," the President of the HPSC, Sayaka Kinoshita, replied as she looked up from the transcript in her hands.

"Everything he said was the truth. Or at least he thought it was," Naomasa Tsukauchi returned, All Might at his side.

It was the only reason the police detective agreed to disclose his findings like this.

"That line about the three marginalized peoples… it kinda rings true," Keigo Takami, current-No.3 and soon to be No.2 Hero: Hawks, admitted as he scratched at his cheek. "And if we take his word as gospel-"

"Let's not get into the meta-commentary and just focus on what's in front of us," the madam president cut in. "Detective Tsukauchi, can your Quirk detect if someone's memories have been doctored?"

"No. And that's a common-enough trick that even a civilian would know about it beforehand," the man said shaking his head. "We'd need a mind-reader of some kind, and myself in attendance as well so I can ascertain the veracity of their commentary."

"You think someone would lie about their findings?"

"It's always been a concern whenever someone with any sort of mind-delving Quirk is involved, as opposed to tangible evidence," Naomasa stated. "Like I learned at the academy, 'people lie, stuff doesn't'."

"And it isn't like we can find any physical evidence," Hawks replied. "When this Kenji guy body-swapped with All for One, his original body died from blood loss moments later and took All for One with it. It was only because he was in shock that he was able to make the switch at all. He was not in good shape when the rubble came off."

All Might remembered as such. He had stayed on hand in the event that All for One had been playing possum and the whole thing was some kind of ruse. A legitimate concern, given All for One had literally suckered him all those years ago with the same act.

After the body of All for One had been carted away in the highest-level of Iron Maiden, completely inert, it was determined conclusively that the body of Kenji Sato was clinically braindead with all vital functions ceased, and no way of them restarting. Not with half the bones in his body crushed like gravel and his entrails spilled out like a busted toothpaste tube.

"So say we get a mind-reader down to his cell and we ascertain that this actually is a desk drone that body-swapped with the most-powerful Villain in the history of the world. What's our next play?" the madam president inquired.

All Might may not've been the No.1 Hero anymore, or even a Hero period, but the man's decades of experience and all the good he did couldn't be denied. Or at the very least, she wouldn't be the first person to brush his counsel off. That, would be political suicide.

Of course, once that first domino had fallen, All Might's influence would rapidly evaporate. This could very well be the last thing he could do to influence policy outside of being a schoolteacher.

"Ideally, we'd release him from Tartarus so we don't simply create another All for One out of spite," All Might began. "He'd need constant care and attention afterward since, not only will he be functionally invalid until he learns to use All for One's stolen Quirks, but the League of Villains may also try to get him back. Even if they can't get him to cooperate with their aims, they might not be above turning All for One's body into a Nomu and simply mechanizing the process of stealing and transferring Quirks."

"Also, if we can get Mr. Sato to cooperate, this could be a tremendous boon," Hawks added. "The most-recent Quirk that All for One stole was Tomoko Shiretoko's [Search], an extremely powerful meta-ability that would've allowed him to keep track of countless people, even all the way down in Tartarus. If it were still All for One behind the wheel, there isn't anything we could give him to make him give it back, and no-one with a Quirk-activating Quirk would want to get close-enough to try."

"But say we do ask Mr. Sato to give back Ms. Shiretoko's [Search]. What about all the other stolen Quirks in his body?" the madam president inquired.

"In all likelihood, the other people whose Quirks he's stolen are all dead. If he left a trail of Quirkless people in his wake starting years ago, I'd have realized right away that All for One was still alive," All Might answered somberly. "People 'disappear' all the time, but people don't magically become Quirkless anymore. Not since Quirk Evaporation Syndrome vanished from the face of the Earth."

"Well, apart from you, but those are extenuating circumstances," the madam president replied as she turned her eyes to All Might's emaciated form.

"So then we're in agreement. We ascertain if this really isn't All for One playing another of his head games, and then we take Mr. Sato into our protective custody," Hawks stated.

"Actually… I would like his protective custody to be served by Yuuei," All Might spoke up, causing everyone's eyes to go wide. "Obviously, having someone with All for One's Quirk in such close proximity to the next generation of Heroes is far from ideal… but I feel like it's my responsibility to look after him. Mr. Sato only got into the position he was in because years ago, I let All for One slip through the net. If I'd been a bit more paranoid, a bit more attentive, All for One's comrades wouldn't have been able to spirit away his body at the first opportunity. Sure, Mr. Sato would've still been functionally Quirkless, but at least he'd have been in his original body, instead of a beat-up cadaver that can't even see anymore outside of using stolen Quirks."

"And what does Principal Nezu think of this, and the other Yuuei staff?" the madam president inquired.

"We're hoping that Mr. Sato, if this really is who he is, giving Tomoko her Quirk back could garner some measure of goodwill," Naomasa stated. "I certainly know that she would appreciate having her Quirk back. As she is now, she'll either have to retire from being a Hero and become a first responder, or simply retire altogether and live off her pension, if not get a soul-sucking job and become a desk drone. Unironically."

"Before we try to set anything in stone, let's see if this really is a 'Reincarnator' with a 'Cheat Ability'," the madam president replied, her face showing how-ridiculous she felt saying as such aloud. "And for god's sake, don't let it get around that this is what's going on. The easiest explanation is that Mr. Sato had a body-swapping Quirk he had the moral fortitude never to use for personal gain. That's all anyone ever needs to know about this. Understood? I'm swearing us all to secrecy on this. The transcripts of your interrogation will be classified to the highest degree imaginable and none of us will ever speak of what we discussed in this room to anyone ever again."

There were unanimous nods from all around.

If you started going down the rabbit hole, you'd never stop.

*SIAFO,SW?*

AN:
This whole thing started off as a plot experiment in a "What If…?", and in terms of MHA stories I'm writing, this one starts further down in the timeline than my previous works. Vigorous Vitality started at the Sports Festival Arc with ties to My Hero Academia: Vigilantes, while Another Hero Academia: Out of Time begins well before the first episode prior to the beginning of My Hero Academia: Vigilantes.

Don't know if someone else already did a story like this, I didn't actively look, but I'm hoping the idea is unique-enough (someone stealing All for One's body, not someone possessing the QUIRK [All for One]) that it hasn't already been done.

Anyway, tell me what you think of the Intrigue, and I'll see you all next time.

CHANGE NOW!