Deku has Kimmimaro's Bloodline Limit from Naruto. All For One does some poaching. (Graphic Violence warning)

Bloodline Limit Deku: Dead Bone Pulse

"You wish me to take your quirk?" All For One asked, leaning on the arm of his chair. The sound of mechanically aided breathing echoed through the room.

"I do."

This wasn't a unique occurrence. Many times over the years, All For One had been approached by those whose quirks were more of a curse than a gift. Sometimes he would accept them, if they interested him. Other times he would just kill them, their quirks not remotely suitable for his purposes, or just were too much of a detriment even for him.

It had been a long time, though, since someone had asked him this. Not since the days before All Might started his self righteous crusade against All For One's Kingdom of Evil. Maybe if All For One had actually read the end of the comics he loved as a child, he might have known a way to prevent the hero's victory. Oh well.

His revenge would be sweet, once Tomura was ready.

He returned his attention to the young man before him. He was impressed the boy had even learned of him. All Might and the government had gone to great lengths to hide his existence. Reduced to nothing more than an internet rumour. It was almost laughable, but also useful for his vengeance.

"How did you learn of me?"

The boy looked down, his long green hair falling over his eyes. "When I awakened my quirk, I was happy. It's a morbid quirk, but with it I believed I could be a hero. It's flashy and powerful, so I thought I had it made. I believed I could be like my hero, All Might!"

Ah, a disenfranchised hero wannabe. And an All Might fan, to boot. This could get interesting. The gears began to turn.

"But everyone called it a creepy quirk. They said I'd be better off as a villain, that I'd just scare anyone I tried to save. So, I ignored them. But eventually I started to get sick. I would cough and blood would come out. I went to the doctor, and they said that it was because of my quirk. I didn't believe them!" the boy shouted, clenching his fists. "I thought they just wanted to blame my quirk, because of course my quirk had to be to blame!

"I got treatment, but as time went on, more and more supposed evidence came forth that it was because of my quirk, so they stopped! I started to maybe believe it. I liked my quirk, but if it's killing me, I don't want it! So I looked online. Tried to find a way to get rid of it. But nothing came up. No surgery. No drugs. Nothing at all!

"But, there were rumours. Rumours of an overlord who could take and give quirks at will! I knew I had to take the chance. I was given five years to live recently, so I started looking online. I even looked on the dark web. And over time I found little bits and pieces of info, little rumours. Until they led me to one of your agents, and when I said what I wanted, they brought me here."

The boy hunched over, gripping his knees and panting. It was quite the monologue. Almost manic. All For One leant back and folded his hands. "I see. And so, you decided to foist your deadly quirk onto me?" he said, and, for the heck of it, put the full force of his Demonic Presence onto the boy.

The boy trembled, but he stomped a foot down to maintain his stance. He looked through the curtain of hair that hung over his face. Scared though they were, his eyes were solid with determination. "I-I don't want to inflict this curse on anyone else. I-I figured if you could take quirks, you could also get a good idea of what they are before taking them. S-So I thought, if you could just confirm if my quirk is the cause of my disease or not...I-I don't know."

His head fell down again, and he gripped his knees to the point his fingers turned white. "R-Regardless of what it is, feel free to kill me afterwards. I'm going to die, anyway. But before I do...I want to know if my quirk doomed me from the day I was born, or if it's something else." The boy finally dropped to his knees, but it was only to press his forehead on the floor in a bow. "P-Please. I'll do anything, I just...want to know…"

All For One hummed. He felt his mouth twitch. This boy...there was a potential there. "Come closer, child. Approach my throne."

The boy stifled a gasp. He quickly but respectfully approached, and took a knee. "Th-Thank you, sir."

All For One laid a hand on the boy's head, and felt.

Hmm, how intriguing! A fascinating quirk...if he didn't already have all of the components from the various quirks he'd gathered over the years, he'd be very tempted indeed. However, he had some good news for the boy. "Those doctors were lying, child. Your quirk is not to blame for your illness."

The boy stiffened. Trembled. Drops fell to the floor. "Th-thank you, sir…" The boy's body relaxed. He had put himself at the mercy of a Demon King.

And dispute All Might's belief, mercy he could give.

The boy gasped as All For One did it's work, and All For One smiled. He removed his hand, and the boy looked up, green eyes brimming with tears and confusion. "H-Huh?"

"I gave you a quirk, child. Superhuman Immune System. With this quirk, illness and disease should be of no concern. Your own quirk will do the rest of the work, and your body will heal. You...will live."

The Doctor had several copies of that quirk one hand. It would be a simple matter to regain it.

The boy's eyes widened. Tears welled up and spilled over, pouring down his face. His face fell into his hands, and he sobbed. "I-I…I'll live?"

All For One allowed the boy to have his moment. Then, he spoke. "You've had a rough life, haven't you, child? Society has shunned you, the doctors who should have helped you let their prejudices get in the way of their oath. All because your quirk goes against the grain. What is considered 'good'."

The boy's sobs stopped, and although All For One couldn't see his full face, he knew the boy was listening.

For when All For One saw the eye that peaked through those fingers, he saw something that he knew he had to nurture.

Hatred.

"Would you listen to me, for a while? It is the only payment I ask for that quirk I gave you."

And when the boy nodded, All For One grinned behind his mask.

He could give the boy's quirk to a Noumu, but he had other plans.

My apologies, All Might. But I do believe I've stolen your fan!

Izuku followed Tomura through Kurogiri's warp gate. So, this is the USJ? he thought, not a single trace of emotion passing his face. Once upon a time, he would have been nerding out at the thought of being inside a UA facility. But that was the old Izuku. The emotionally weak loser who tried to get by in a society that rejected him for how he was born.

His bones itched for a chance to show their might. For too long had he held himself back, fearing the response. Quirk laws and social norms bound him no more.

Noumu stepped up next to him. Izuku was impressed at what Sensei and the Doctor were capable of. The Anti-All Might weapon.

His bones shifted at the thought of that man. He hadn't told Sensei about his meeting with the Number One Hero, because the memory was humiliating. Of course asking him if someone terminally ill could be a hero would end in only one way. But the inevitable response had still destroyed him.

It was the final straw that made him search for All For One. And now he could be part of the death of the man who birthed his dreams, and then crushed them. Like he couldn't have humoured a dying kid? So what if Izuku sped up his demise, he hadn't had long left anyway, might as well go out doing what he always dreamed of.

No. It was seeing Izuku's quirk that made All Might say that, he was sure. He'd seen the flinch, small as it was, when he showed him his bones.

Eraserhead leapt into the fray and started laying the beatdown on the thugs they'd brought with them. He was impressive, but the man didn't have eyes in the back of his head. As Eraserhead landed after taking down a large mutant, the man paused to use his quirk on another group.

Izuku pointed at the man. He pushed two of the phalanges of his right hand out and fired them into the back of Eraserhead's left calf. The bones had regrown by the time the man fell to a knee, and Izuku used them to fire into Eraserhead's left elbow.

The power of a pistol, without any of the obnoxious noise. And that was only the most minor of his quirk's deadly applications.

With two limbs crippled, it was child's play for the thugs to surround the hero and rip him to shreds.

"Huh," Tomura said. A single eye peaked out between stiff fingers. "I was observing him. It would have been cool when I figured out his weakness," he said, sounding annoyed.

"I saw my shot, and took it," Izuku said, lowering his hand. He was a little disappointed. He'd researched Eraserhead. It had been hard, but what he found pointed to a competent hero. Sure, he'd been distracted, but he also should have known better than to leap into a horde of villains by himself. As if someone couldn't take advantage of his turned back in time. Arrogance.

"Shigaraki Tomura," Kurogiri said, reappearing. "One of the children got away."

Ignoring Tomura's mental episode, Izuku looked to Kurogiri. "Send me to the plaza. I'm not satisfied." He hadn't had a chance to fully see what his quirk could do in a fight. Sniping Eraserhead didn't remotely count.

Kurogiri nodded and a second later Izuku was in front of some hero students. Thirteen lay on the ground, seemingly unconscious. But alive, judging by the breathing.

"W-Who are you?" a girl asked. She had pink skin and hair. Interesting.

"A villain?" A boy with black hair and bulging elbows said.

"B-But he's our age," another girl said, this one with pink cheeks.

"Eraserhead was disappointing. Maybe you will be more of a challenge."

"Wh-What do you m—" the pink girl looked to the plaza, and interrupted herself with a scream. "AIZAWA-SENSEI!?"

The pink cheeked girl threw up in her helmet, and a large boy with multiple arms went wide eyed. "H-He's…"

"D-Dead?!" a muscular boy with large lips said. He said no more as a phalange went through his eye. The girls screamed again as his limp corpse fell. The elbow boy roared as he fired tape from his elbows. Izuku extended his humerus from his wrists and sliced through the tape with their sharpened points. He fired one at the boy, and he fell clutching his stomach.

Izuku let the giant wrap his many arms around him. "I won't let you kill anyone el—" Izuku's rib cage and spikes of bone from his arms pierced through the boy, one going through his heart and another through the brain. He retracted his bones, letting another corpse hit the ground.

The girls sobbed, but the pink one glared through her tears and fired a substance from her hands. Izuku raised his arms, letting the acid splash against the bone that he'd pushed through his skin. His bones could repair themselves faster than the acid could eat them away. Her last act was to stand, mouth agape, and Izuku's distal phalanx shot from his big toe and went in her mouth and out the back of her neck.

"Too easy," Izuku muttered. He looked at the corpses and the grievously injured, feeling nothing. Shouldn't he feel something? No, he did feel something. "These are the sorts of quirks that are considered worthy of heroics?" he said, under his breath. "My quirk was looked down on for being villainous, but that girl could shoot acid?" A small smirk tugged at Izuku's lips. His quirk proved superior, regardless.

He knew now. They were just scared. Scared of his potential. Perhaps if the fools hadn't treated him like a villain to be, he wouldn't have walked down the path.

Izuku approached the last girl and the prone Thirteen. The girl trembled on the floor, a dark stain creeping across the bottom of her costume. He shoved his remaining humerus through her head as he passed. He pulled it out, then shoved it through the dark screen of Thirteen's helmet.

As he removed the bone, the doors of the USJ slammed open. Izuku made eye contact with All Might. It was only instinct that made Izuku cover his entire body with thick bone armour, and it was what saved him when All Might slammed his fist into him.

When Izuku came too, he was lying in the remains of a building. How did he— oh, this must be a zone in the USJ. He stumbled to his feet, shattered shards of bone falling to the ground around him.

Izuku fell to his knees and coughed. He glared at the red staining his hand, an unseemly reminder of recent hardships.

"What the sh— DEKU!?"

Oh great. This guy.

"Hello...Kacchan." He smiled, a thought occurring. "I'm glad to see you, actually. I have a bone to pick with you."