Author's Note: This story is an AU of chapter one rather than a sequel. What would have happened if Izuku had body-swapped with someone else instead?

Izuku's fingers shook as he hung up on his dad. No, All for One didn't deserve to be called a father! How dare that smug basted act like of course Izuku would come around to his side eventually?

In his anger, Izuku didn't notice a General Studies student running up the stairs, no doubt late for class. They collided into each other. Arms flailing, she fell backward—teetering at the top of the staircase.

"I'm sorry!" Izuku cried, leaping forward to grab her.

At the bottom of the stairs, Fumikage took flight to catch the girl.

Unfortunately, all three of them collided in mid-air. Izuku and the General Studies student smashed their foreheads together with a painful crack. Purple light consumed both of them.

Izuku was flying. Wings moved like part of his own body. Even with no clue what was going on, he reacted on instinct to catch two falling people.

In one arm, he held the knocked-out General Studies student. In his other, he held his own unconscious body.

"Somehow, this is all my father's fault," Izuku said in Fumikage Tokoyami's voice.

Sitting in the principal's office, Izuku asked, "Does the body swapping quirk wear off?"

Nezu placed his paws together. "I'm afraid not. However, the user can easily swap the two of you back as soon as she wakes up. She and Fumikage are currently in the infirmary."

Izuku nodded. His head felt oddly heavy with feathers and a beak attached. That would take some getting used to. Or rather, hopefully he wouldn't be stuck like this long enough to need to get used to it. "What a relief. I wouldn't know how to tell All Might that I misplaced One for All."

At that horrible thought, his arms tensed. A green spark raced down them.

"Huh. I don't think I did lose it after all," Izuku muttered. "But then do I have Dark Shadow or not? I have a bird's head, but does that count as a quirk?"

His musings were cut off by an alarm.

The first step of Hisashi Midoriya's plan had failed. His son had refused to pick up his phone and hadn't left U.A. after class let out. Thus, Hisashi couldn't deliver the (entirely fake) warning that the Hero Public Safety Commission had ordered his arrest.

But All for One always had a backup plan.

Hisashi lurked outside the school infirmary—the very first place he'd looked for his son, absolutely no surprise to find Izuku there. He watched through the window. An unconscious and irrelevant girl lay in one bed. On the other, Izuku sat up and rubbed his eyes.

The two men entering were real employees of the Hero Public Safety Commission—but they'd been bribed by All for One to carry out his orders.

Holding out his badge, the first man said, "Izuku Midoriya, you're under arrest for suspicion of spying for your father, All for One."

"How dishonorable!" Izuku scowled. "I'm disgusted by your behavior. My friend is no villain, and only a fool would hold his parentage against him. Izuku, you run while I hold them off. Prepare to be absorbed by the darkness!" He raised his hand.

Nothing happened.

"Hmm? Dark Shadow?" Izuku looked around with increasing confusion. He felt at his own face, lingering over his nose, then his confusion turned to horror.

"Err…you're under arrest?" The double-agent cast eyes at the window where he knew All for One hid. They'd made plans in case Izuku fought back or surrendered, but not this strange reaction.

Hisashi sighed. His poor son must be severely concussed. Best to get this over with so Izuku could receive proper medical treatment.

Breaking through the window and triggering a loud alarm, Hisashi landed on the tiled floor. "Get away from my son!" he cried dramatically. As planned, the Hero Commission men immediately played dead.

"I'm not your son," Izuku said from the bed.

"Yes, yes, even if you say such cruel things, I'll still always love and protect you." Hisashi wiped a tear from his eye.

"No, I mean, I'm not Izuku Midoriya." Izuku stared at him.

Hisashi frowned. "Normally you're more skilled at deception. Have you seen a doctor yet for your head wound?"

"No," Izuku admitted. Then he screamed at the top of his lungs. "Help! Villain!"

"U.A. allowed the authorities to arrest you. No one is coming to save you," Hisashi lied. "Aren't you surprised and disillusioned? The Hero Public Safety Commission no doubt knew you were innocent but planned to take you hostage to use against me."

"Pshaw. The depths of darkness hold no surprises for me. I expect no better from this miserable world drowned in sin." Izuku crossed his arms. "God is dead. Society is a lie. Nothing matters."

Hisashi blinked. He'd wanted to mind-break his son but he'd never expected it to happen so fast! Had Izuku been through some terrible hardship unknown to himself? His eyes narrowed. "You're not attacking me. You didn't attack those men, either. Can you use One for All?"

"What's a One for All?"

Taking that as a no, Hisashi advanced. He'd originally had a much longer plan involving wearing Izuku down mentally and physically. But why not take advantage of this stroke of luck?

Using a sleep quirk, he easily knocked his son out. Then he flung Izuku over his shoulder and carried him off as alarms continued to ring.

Hisashi waited in a chair by his son's new bed. Doctor Garaki had already checked Izuku over and assured him that the head injury was mild. The quirk suppressant bracelet around his ankle would ensure that pesky quirk would stay unavailable.

Groaning, Izuku rubbed his eyes. As he stared at the steel walls, his pupils doubled in size.

"How are you feeling?" Hisashi cried. "Do you need water?" He held out a cup.

Izuku looked at his outstretched arm as if it held a spider. "Am I in a bank vault?"

Hisashi chuckled. "It's a bit of a family tradition." He gestured at the wheel on the metal door. "Isn't it nice and cozy in here? And safe. Very safe."

In a deadpan tone, Izuku said, "I have seen crazy, I have even been hung with the label myself in my more dramatic middle school days, but surely thou art the craziest."

"Ah, you're getting a bit of sass back! Glad you're feeling better, son."

"What a mad banquet of darkness…" Izuku rubbed at his hair, seeming to find his own locks fascinating. "About the 'son' situation. Am I safe in assuming that you would have no compunctions about murdering any hero student not related to you?"

"Without hesitation! It's a villain thing," Hisashi said cheerfully. He wanted his son to be aware that all his classmates were potential hostages.

"In that case, yes, I am Izuku Midoriya. I lied earlier. To avoid being kidnapped like this." Izuku smiled as if the concept of lips was unfamiliar to him.

"I'm sure you'll come to like living here. I've stocked this room with everything you need." Hisashi gestured at the shelves. "I even have comic books and hero merchandise—everything but All Might, I couldn't bring myself to include him."

Izuku's eyes widened. "Is that a first edition Odd Eye figurine? He's my favorite hero!"

"Your favorite? I thought All Might was your favorite?"

Izuku looked like he wanted to sink into the floor. "I completely understand why you would make such an assumption. After all, I idolized him as a child. But upon reaching an older age, I realized that a creature of light did not suit a creature of darkness such as myself, and my tastes evolved."

"Huh…that way of talking…"

Izuku tensed.

"You sound just like me in middle school!" Hisashi beamed. "I went through a chuunibyou stage, too. Truly, you're a chip off the old block! I'm so glad you finally got over your All Might phase. We'll work on weaning you off heroes entirely."

Izuku muttered, "I count myself fortunate that villains are so self-centered."

Hisashi was about to launch into a brilliant rebuttal, but then an alarm announced an attack on his hideout.

Hisashi had expected an army of heroes. Instead, one lone U.A. student with a crow or raven's head stood before him.

"All for One! Get out here!" the bird-headed student bellowed. "I won't forgive you for involving my classmate in this! Fumikage had better be unharmed!"

Being a genre-savvy villain, Hisashi had to consider the possibility that this was a trap. He approached from a safe distance. "Who is this Fumikage you speak of?"

The unfamiliar boy glared at him. "You didn't even notice, did you? You're the worst father ever!"

Hisashi didn't have to take this from some second-rate hero wannabee. "And you're a fool to have come here alone." His palms glowed red.

"I'm not alone." The boy spread his arms wide.

Eight shadows coalesced around him. One had spikey hair and gauntlets on his arms. Another a ponytail with a bandana. A shadow with shaggy hair stood flanked by a bald man and a short man with a high collar. Their features were indeterminate, but their eyeholes burned with green light.

In spite of himself, Hisashi took a step back. He rarely bothered to remember the people he'd killed with any detail, but he knew that light. "One for All?" His eyes fixed on the boy in the U.A. uniform. Several clues slotted together. "You're Izuku?"

"It's not him you should be concerned with," Nana Shimura's shadow growled in a voice like gravel. Darkness dripped from the tips of her hair. A slasher grin split open her face.

"Your time of reckoning has come, big brother." The newest shadow spoke in a very familiar voice. Whisps fell over one eye. His other eye was shaped like a spiral. Glowing green light dripped down from the eye socket like blood or tears. Sharklike teeth bared in a twisted smile.

Hisashi's heart raced a mile a minute. Indescribable emotions flashed through him. He nearly reached for the shadow of his brother. Then his self-preservation instinct kicked in. Decades of battle experience screamed at him to retreat.

The last shadow formed into an outline of All Might. In a static-filled voice, it whispered, "You…couldn't….even….recognize…Izuku. I'm…the…better…dad."

"You are not!" Losing all sanity, Hisashi attacked.

Eight shadows fell upon him.

Izuku watched as the vestiges took out centuries of rage on their fated nemesis. None of All for One's attacks affected the shadows. They one-sidedly pummeled him, surrounding him on all sides to prevent him from running.

"This is beautiful." Izuku wiped a tear from his eye as Nana repeatedly kicked All for One in the crotch.

After the screaming stopped, Izuku said, "Fun though this has been, we should go rescue Fumikage. I'll let you kick All for One some more later, Nana."

En dragged over a long chain. "I found this inside the villain's hideout."

Several vestiges set to squabbling over who got to tie up All for One.

Yoichi drifted over. "I can guide you to where your friend must be held captive. My brother is super-predictable: the bank vault is always in the basement." His smile broadened, quite literally stretching open his face. "Aw, it's so great to be able to talk to my cute little nephew like this! Can I have a hug?"

"Sure," Izuku said, patting the dark shadow. It felt damp and cold, like touching an unusually solid cloud.

Nana ruffled Izuku's feathers from behind. "Group hug!"

All the shadows pounced on Izuku.

En rambled, "You're too skinny, you need to eat more. Nutrition is very important for a growing boy. So is sleep. It might help you break fewer bones."

"We're all very proud of Izuku and his bone-breaking determination," Yoichi said.

"Super-proud of him," Banjo agreed. "But let's take advantage of our temporary corporality to teach him a few tricks about how to use us without getting injured."

"My quirk will help with that." Hikage smiled, an expression just as creepy on him as the other shadows.

The shadow who resembled the Second muttered, "Don't listen to Yoichi, he's a reckless dumbass."

"Hey!" Yoichi cried.

"It's true." Nana snuggled Izuku. "You might be a bad influence on our child."

"Excuse me? There's no our child! I'm his uncle!" Yoichi dragged Izuku away from her.

Toshinori's shadow latched onto Izuku's other arm, making possessive growling noises.

Izuku said, "Everyone, we should get moving before All for One wakes up."

This sobered the group. Izuku grabbed the chain and dragged the unconscious All for One into the building. The shadows helped him carry the weight. His prisoner's head bounced off the ground as they walked, but Izuku didn't see that as his problem. Nana stood ready by All for One's head to kick him unconscious again if need be.

At the bottom of the stairs stood a round metal door with a wheel.

"Allow me," Yoichi growled. He reached forward with dark hands and ripped the door out of the wall. Then he ripped the metal into four separate pieces.

Fumikage leapt to his feet. "Me! I mean Izuku! You're inhabiting my mortal shell, Izuku, is that correct?"

"That's right." Izuku tried to smile reassuringly, but it didn't work with his beak. "I'm sorry you got dragged into my family drama."

"I'm sorry you have to deal with such a messed-up family. I'm going to go home, hug my father, and tell him how much I love him." Fumikage stared All for One. "Is that—"

"Yup."

"How did you—" Fumikage's voice cut off as he examined the eight shadows. "What happened to Dark Shadow?"

"Who knows? My quirk is a bit unusual." Izuku chuckled sheepishly.

"We are One for All, the doom of All for One." Yoichi's eyes glowed green.

"We carry the torch of nine generations of heroism," Hikage said.

"We are that which cannot be stolen even by death itself," En said.

"And having defeated our greatest enemy, we demand a tribute of pocky!" Banjo cried. The others glared at him. "What? Don't you want to find out if we can eat in these bodies? Don't tell me I'm the only one who's been thinking about it."

"Izuku, your quirk is the greatest chuunibyou of them all." Fumikage sounded like he meant that as a compliment.

In an attempt to avoid further questions, Izuku said, "Let's head back to U.A. so we can swap our bodies and you can get your quirk back."

Just as they'd almost reached the door, Tomura stepped into the hallway. "What's that noise?" His eyes fell on the chained-up and bleeding All for One. "Ah! Sensei!"

"Hey, grandson!" Nana tackled him. "Try to tell me that you hate me now!" She put Tomura in a headlock. He gurgled, tugging on her hands. But he couldn't decay her. His eyes rolled backward, and he passed out.

Izuku tossed Fumikage the chain. "If you can drag him, then I'll carry Tomura. I'm currently taller."

The two of them set off for U.A. Academy with their two prisoners. Izuku chirped a cheerful tune under his breath. He'd captured two of Japan's top villains! All Might was going to be so proud of him!

(All Might was definitely proud. And confused. But also proud.)

OMAKE TIME!

Omake: The Second Gravest Insult Next to All Might Calling Himself the Better Dad

First: Big brother, I'm taller than you now.

Hisashi: Oh no, you didn't!

#

Omake: If Only First Turns Into a Shadow

Hisashi: Christmas came early! (Picks up First's shadow and runs off with it. Reappears moments later covered in bite marks.)

Izuku: Hey, give my quirk back!

Hisashi: I'll take you to where he is shortly, just step into the vault.

#

Omake: Deadbeat Dad

Izuku: All Might was right about you being the worst father. You couldn't tell that I'd been body-swapped, twice! You figured it out with Fumikage faster than Mineta! Mineta!

Hisashi: The Mineta chapter…was not my proudest moment. In my defense, Mineta was trying to deceive me and Fumikage wasn't really.

Izuku: And you got fooled by the likes of Mineta? Maybe if you stuck around when I was a child, you'd recognize your own kid. Deadbeat.

#

Omake: The Epilogue

Izuku: One for All, I need you to give Fumikage's quirk back. Gosh, it feels strange talking to my quirk like you're a separate person, but according to the vestiges, you're the reason why he hasn't gotten his quirk back even after we returned to our correct bodies.

Voice Behind the Vault Door in the Void: Shan't. Won't. You can't make me. I like how it tastes.

Izuku: Please. Dark Shadow is more than a quirk to Fumikage. They're friends. Please, give it back.

First: Let me try. The longer you don't let go of bird-boy's quirk, the longer I keep talking. When my brother was in middle school, he developed severe chuunibyou syndrome and became convinced that he had a quirk letting him cast curses of people. Of course, as later history proved, he was completely wrong. So he went to school one day wearing this ridiculously goth outfit and went around cursing people—

Izuku: Hey, that worked! The quirk is gone! Hmm, why exactly did telling your older brother's embarrassing stories affect One for All?

First: Who knows? It's a total mystery.

Author's Note: For future body-swap AUs: who else would it be fun for All for One to accidentally vault instead of Izuku?