An alternate version of the AfO fight I briefly entertained but eventually didn't choose!

~

Izuku's whole body was in agony. Opening his eyes was a mistake, as the light jammed spears through his skull, but he struggled through the pain because he knew he was in the League of Villain's base after stupidly leaping for Kacchan and ending up tumbling through the portal with them. Hands were wrapped tightly around his biceps and his feet were dragging along the wooden floorboards, and when he blearily glanced around he realised he was being carried through the hideout.

Every move made his stomach clench with nausea. His head lolled to one side and he squeezed his eyes shut again, feeling himself sway as if he was on a boat as he was pulled through the corridors, which certainly didn't help his sickness. One of the villains was talking a lot and kept switching tones, sometimes bouncing along and sometimes trudging, and the shift kept jarring Izuku's shoulder whenever he bounded forwards. The hands on his other arm were unnaturally warm, like Shouto's, and a dazed blink to his right confirmed that Dabi was holding him.

Dizziness swirled through his mind, only clearing when he was suddenly dumped in a dimmed room, landing heavily on the floor. He slumped against the cool ground, trembling with the hot pain that rolled through his small form.

"Now, is that any way to treat our guest?" A deep voice rumbled, followed by a rasp of a breath.

No. Izuku's blood froze. It couldn't be. He pressed his fingertips against the solid surface beneath him, shaking with the effort it took to push himself into a sitting position, intending to try for intimidation but failing as he gagged with another flood of nausea that came with the sudden movement. His eyes were squinted and he pressed a palm over his mouth, glaring defiantly up at the hulking figure sitting in the shadows, pipes and tubes trailing from his silhouette.

"I knew I made the right choice in bringing you here, Midoriya Izuku," All for One drawled, his tone low and threatening, and yet somehow laced with saccharine playfulness. "Shigaraki Tomura wanted you dead, but I persuaded him to let me speak with you, because I believe you have much potential."

Izuku couldn't speak. Whether it was because his head injury had merged his knowledge of language with his random facts about birds, or because he was frozen with terror in the dreadful aura that this villain gave off, he wasn't really sure. He snapped his teeth together loudly, lowering his hand to reveal a shaky smile and repeatedly reminding himself that he was scarier than this monster, and he was as powerful as All Might, but he was also smart, and he needed that to get out of this situation alive.

"I find it peculiar that these heroes you look up to are unable to protect you, and you're left to fend for yourselves, even though you're just children. Training you so violently and ruthlessly from such a young age... It's truly awful," he said with a faint shake of his blank head, as if he was actually capable of feeling genuine human emotions. "Even All Might is encouraging you to fight, isn't he? Although, I suppose that's because you're his successor, aren't you?"

The boy stayed silent, forcefully swallowing against the rising disgust. Although he didn't want to, he gave into his instincts and dipped his head slightly, squaring his shoulders and acting feeble and submissive.

All for One chuckled faintly, with a cold imitation of sympathy in his tone. "Yes, I thought so. I almost can't believe that he's stooped so low as to get a child to fight for him. Has he told you the history behind your Quirk? Do you know that you're expected to fight me? Do you know that every other holder of One for All has died by my hands?" He sighed, resting an elbow on the armrest and lightly pressing a fist against his scarred cheek to prop up his head. "You probably think I'm a terrible monster, but I didn't want to kill them, you know. I offered them chances to join me and become greater, because I recognised the potential in them that the heroes refused to acknowledge. Of course, none of them took that offer, and I had to defeat them in self-defence."

Izuku didn't know if his sudden awareness of his Quirk in his veins was just because of his desire to fight or because it was responding to the reminder of its previous holders. It was a struggle to keep it locked under his skin. He moved to wrap one painful arm around his torso, slumping a little lower and letting his blood-matted hair conceal his face.

"Hero society is terribly corrupt. Heroes are punished for their mistakes, as if people forget that they're human, too. It's strange that the idea of learning from one's mistakes has been put aside. If you become a hero, you face heavy scrutiny, and just a single slip-up is enough to ruin your career." All for One linked his hands in his lap, shifting his position in his chair to be a little more relaxed, carefully engineered to appear more inviting. "I'm not heartless. No-one should go through that. I especially don't want you to go through that. Imagine the struggles you'll face when people realise you were mentored by All Might himself. Imagine the expectations of greatness they'll have for you. Imagine how disgusted they'll be if you show a single hint of being anything but perfect. Isn't that awful?"

Izuku hesitated, then nodded slightly, as if he was lapping up every persuasive word the villain spewed like vomit. He scrunched himself smaller, suddenly shaking his head more aggressively as if he'd just realised what he'd done and regretted it.

"Yes, I understand how confusing and upsetting all of this must be. Just like every other child, you grew up in a world where you were indoctrinated to blindly trust these heroes. To have someone like me point out the flaws must be really earth-shaking... However, I believe that you're smart enough to realise that your power is wasted with the heroes. You can barely even use One for All without breaking your own body, and they haven't even tried to teach you how to use it properly. What sort of hero allows a child to hurt himself, over and over, without doing anything to help?" All for One continued, a sort of pout to his tone, like he was coddling a toddler. "I know you can be great, Midoriya Izuku; but your love of heroes is holding you back. You need to realise that they're not as wonderful as the media try to make them out to be."

A perk of being a Midoriya is that he could cry with immense ease at any given moment. He let out a soft sob as tears rolled down his bloody cheeks, and he briefly gazed up at the abhorrent villain with fake hope in his expression before he raised a hand to his messy hair and forced himself to stare down at the floor again. Izuku had learnt how to subtly manipulate situations into his favour during his years as a hero, and it was clearly working, much to his relief.

"I'm sorry, young one," he soothed, except his voice was made of razorblades and death instead of comfort and love. "I know. I'm really sorry to have to be the one to break it to you. But you're not alone. You don't have to be afraid anymore. You don't have to hurt anymore. If you want, you can stay with us, and I'll teach you everything I know. If you make a mistake, it doesn't matter. I'll do anything to help you learn and grow. Do you want to be safe, Izuku?"

Oh, god – the way he said his name almost made him throw up. Izuku clenched his hand tighter into his exposed side, into the scar across his abdomen from the Hero Killer. He let himself tremble for a little longer, trying to wipe away his crocodile tears, before inhaling deeply and giving a short, sharp nod.

"Thank you for having faith. Now, would you like me to heal your injuries? I'm sure you must be in terrible pain."

*

Izuku sat in the darkness, pressed into a corner. He fiddled with his armour-bracelet and glared down at the ground, filled with spite and restless energy because he knew All Might would soon be fighting All for One, since the villain had walked off earlier with a few, gentle parting words. There was no knowing what happened to Kacchan if he wasn't there to rescue him, but he hoped that nothing terrible would happen to his friend.

The acrid taste of sewage suddenly spilled up his throat, bringing back bad memories of the sludge villain. He choked out some grey slush, clutching at his neck and squeezing his eyes shut as it sprayed out and encompassed his form. His knees hit the ground and the world smelt of smoke.

"Young Izuku!" All Might's voice was panicked, and if the boy wasn't so busy spitting out the awful substance he would've accidentally responded. "What did you do to him?!"

"I merely told him the truth. He saw for himself that heroes aren't are great as they seem." All for One responded with a taunting smile in his tone.

A large hand came down on Izuku's head and it took every ounce of willpower in his body to not grab it and fling the repulsive villain into the stratosphere. He couldn't help tensing up under the touch, but since he didn't automatically pull away he counted it a win, even if the pained noise from his mentor would forever haunt his dreams.

It was too big of a risk to reveal his unwavering loyalties just yet.

There was an explosion, far off to his right, and it was so familiar that he couldn't help looking over. He pushed himself to his feet, a little shakily, staring as Kacchan fought against the villains. Izuku caught himself just in time before he could bolt off, and instead shrank in on himself, slowly turning to peer up at the faceless villain with as much vulnerability as he could muster.

"S-Sensei... Could you... could you please let Kacchan go?" He said in a wobbly whisper, resisting the urge to cringe when the hand returned to his curls.

"Of course, young one." The villain raised an arm, using some kind of Quirk to lift up Kacchan and pull him from battle, even as he snarled and writhed.

Gran Torino dashed over and immediately snatched him up, dragging him away from the scene. Kacchan looked up and made eye contact with Izuku, who could only stare back at him, blank-faced. The boy turned away, keeping his head dipped to avoid glancing at his mentor, because then his resolve would surely crumble.

"Thank you, Sensei," he muttered quietly.

"My boy..." All Might choked out, sounding equally terrified and heartbroken. "I'm sorry for whatever I did to make you doubt me. I know I'm far from perfect, but... I don't understand. Young Izuku, please... Please, don't stay with All for One. Even if you don't trust me, please... Don't trust him."

Don't lift your head. Don't you dare. Don't do it. Don't-

He lifted his head. His mentor was visibly distraught, with a smile that was more a grimace and the blue light in his eyes fading into the shadows. It was clear he was barely holding himself together, both literally and figuratively, as there was steam coming off of his shaking form that was already battered from whatever blows had been exchanged before the boy was summoned.

"I told you, he's realised the corruption of hero society, and he's willing to help us rebuild a fairer world. I can understand why you chose him as your successor – he's very intelligent and courageous." All for One was undoubtedly gleeful as he kept subtly taunting the hero, reaching up to poke at his own cheeks as he grinned. "Oh, where's your smile, All Might? Perhaps you'll change your mind about joining me now that your precious little successor is with us. Wouldn't that be a great story for the greedy media, hm? Symbol of Peace, All Might, Joins League of Villains."

Izuku bided his time, even as his mentor shrank into Toshinori, looking broken and dejected in the baggy hero suit that was far too bright in contrast to the bleak scenario. The student kept staring vacantly, gradually shedding his timid posture as the villain gloated, suppressing his instincts that begged him to go and comfort Toshinori.

"Would you like to help out, young one? It would be rather poetic if All Might's downfall was caused by his own successor, don't you agree?" All for One angled his blank face down at the boy, who peered back up at him in silence. "Of course, I won't force you to do anything you aren't comfortable with. I understand if this is-"

"No, I want to help," Izuku cut in, tilting his head and drawing back his shoulders, expression impressively unreadable.

Toshinori stared in horror. He was shaking, but he looked horribly resigned to the realisation of betrayal. All for One laughed unpleasantly and a wide smile glinted on Izuku's bloody face like the blade of a knife, threatening and oppressive, bearing promises of brutal violence and the end of an era. The boy pulled off the remainder of his shirt that ripped in the fight with Muscular, displaying the long scar across his abdomen, as well as making the strip down his spine a whole lot more obvious, but the villain was too busy jeering to pay any heed.

"Do you want to go first? I think it would be very educational to see how the two of you interact," All for One commented with another sinister laugh

"No, I think you should go first, Sensei," Izuku said smoothly, eyes narrowing into something sly and fox-like. "After all, he is your nemesis: I wouldn't want to take control of a situation I don't belong in."

"How thoughtful." The villain chuckled, stepping forwards and powering up an arm. "Very well. Goodbye, All Might."

Izuku waited, and waited, feeling the seconds tick by as he saw the power gather in the bulked-up arm. His wicked smile shifted into something gentler and green lightning wreathed around his form, illuminating his gaze and sparkling over his legs as he suddenly leapt up, cracking the earth under his boots. He twisted his torso, whipping around with a kick infused with all of his power, slamming his heel down on the back of the villain's head so forcefully that All for One stumbled forwards.

The boy didn't wait for him to recover, appearing by his mentor's side in a flash with a soft, comforting grin. "It's okay, All Might-san. I'd never abandon you – you know that, right? You mean too much to me."

Toshinori sagged with relief, pressing a large palm over one shadowed eye as he let out a heavy, shaking breath. "I had hoped that was the case, but... I couldn't be sure if he was controlling you with a Quirk." He straightened up, glancing at his successor with worry, fingers hesitantly ghosting over his exposed shoulders. "Are you injured, my boy?"

"No, I'm okay," he assured, pulling his mentor into a brief, much-needed embrace before he turned to stare at the villain with a smirk. "That idiot healed me. He actually thought I'd join him, after all he's done. Clearly he's going senile in his old age."

"It seems I'd forgotten how stubborn One for All holders were," the villain said in a dangerous whisper, picking himself up and levitating above the ground. "It's a shame, Midoriya Izuku: we could've ruled the world together."

"I don't want to rule the world, I want to protect it," he snapped back with terrifying confidence.

"I really am impressed, I must say. Even with the strong persuasion Quirks I used on you, it appears you were unaffected. Perhaps I underestimated you." All for One shook his head, almost sounding disappointed. "Well, no matter. I'll just destroy both of you at once and rid the world of your annoying Quirk for good."

Toshinori expanded into All Might, eyes alight with rekindled determination. Izuku shifted his stance, giving a carefree, cocky grin to deliberately antagonise the villain.

Together, they were going to succeed and beat that monster – once and for all.