Izuku opened his eyes, his pupils dilating as white lights blinded him. He checked the restraints he knew would be there. Thick steel cuffs that covered his entire arm and wrist, nearly a foot thick. Another death, another rebirth, and he could feel that his bones had been altered.
He sighed as he tried to shift even a little, his body strapped to a familiar table in a familiar room. He swore that the table had begun to mold to his body by the eighth year. Wishful thinking on his part, but a kid could dream. A familiar clicking sound began, and the table Izuku was slowly tilted till he was almost standing.
A doctor stood there.
His eyes were sunken with a crazed and manic gleam, as you could hardly tell if he had eye sockets anymore; the bags under his eyes had slowly encroached around the entire circumference of his eyes. He had long, gangly hands that had slowly over the years become bony, and issue couldn't tell if blood even ran through them anymore. The lab coat he wore was meticulous and kept to a disgusting degree of cleanliness.
"Hello, my precious."
The same line, every morning, night, meal, death, rebirth. Every damn time. For thirteen years.
"How was my ticket to immortality? You Pandora box of truths?"
It Itched at Izuku as the doctor trailed his long, bony fingers up and down his naked body in a reverent manner. Izuku knew the man's name, but he simply wouldn't use it. The man had once been normal-looking from what Izuku could remember, but the years locked in this building had changed him. His lean and delicate figure had rotted into a frail and gaunt form, his obsession with Izuku's quirk. Thirteen years of watching this man try and fail to figure out how his quirk worked had become boring; the first few years, he had actually pitied the man. Even if he had kidnapped him from his own bed in the dark of night, then killed his mother when she appeared ready to defend her son to her dying breath.
And she did, she died trying to protect her son. Izuku remembered it faintly; the pain of the doctor's experiments had long ago muddled with his memories. The sound of his mother's scream as the man knelt on top of her, he bashed her skull in with a clipboard. His own screaming as he saw his mother's face distort as blood splattered his own face.
"Well, you know what time it is, precious? Yes, you bundle of secrets, it's time to read about the dinosaurs again."
The doctor had also lost his hair ages ago. Izuku genuinely had no idea how the man was still alive. Izuku himself hadn't eaten in years. His quirk always resets his body to perfect health, full of nutrients and fuel. While Izuku had been mentally monologuing, the doctor had struggled to push the able on wheels through the blank halls until they came upon a familiar room.
"Welcome to my Sanctuary!!"
The doctor exclaimed with a delight that made Izuku sigh. Every time it was the same thing, the doctor would start at one end of the spacious library and take each book individually, then read them one by one, word for word, while showing him the images after he was done with the page. Then he would go until his body would give out or the doctor finished the entire library. There were 4,789 books in the library exactly, Izuku had counted. Half of them were about the chemical makeup of dinosaurs, and the other was every scientific theory book about prolonging life. The doctor if you couldn't guess was obsessed with achieving immortality, it had started on a routine check up on Izukus's quirk when he was a kid when they had mentioned although with many tears on Inko's part that Izuku had been hit by a car as a kid and a while later transformed into a strange small lizard thing that was later discovered to be a dinosaur. The only reason he had been able to transform back into his human form was that there was an underground hero nearby with an erasure quirk.
The doctor had been amazed at the applications this could have, then the questions began.
"Do you think it's immortality? Could he be the key to it? What if it could be replicated?"
Those questions had been the reason Izuku had been through so much pain in his life. And the quirk that had caused this fiasco?
Prehistoric Memory
As long as izuku had the intellectual capacity with the right knowledge of bone structure, muscle density, and even blood flow. Izuku could transform into a dinosaur. As had been tested thousands of times, when he died in his human form five minutes and 87 seconds, and 3 milliseconds later, Izuku would miraculously transform into a random dinosaur and live again. And each time he died, his body would undergo a very minor adaptation, allowing him to resist better the thing that had caused his death. Unfortunately for him, the doctor's quirk allowed him to reinforce things, such as his restraints, to whatever multiple he wrote on the material. The restraints placed on Izukus, wrists, feet, thighs, chest, and neck each had the number "100x" etched into it. The only time the effect wears off is when the doctor says so. In his younger years, Izuku had hoped that the hero with the erasure quirk would come and save him, but now that he was seventeen, he had not lost hope, but… he had resigned himself to whatever happened next.
BANG!
Two heads snapped to the door, and Izuku's breath caught. He had never heard that noise before, but years of minor adaptations of having his brain vibrated to mush had altered his ears to hear better but also block out unnecessary sounds. It sounded like one man; he was jogging, clearly cautious, but he was still far away.
"WHAT! Who disturbs my research!! No! NO! NOOO!"
The doctor showed emotion Izuku had never seen before as he angrily smashed the code into the keypad, opening the door and stumbling outside. Hope began trickling into Izuku's chest, and he tried his efforts at the bindings again; they didn't budge as usual, but in his hope-filled drive, he felt that they may have possibly given a little. Outside, Izuku could hear… something, the sound of cloth whipping about as the doctor was screaming about his box. After a moment, it seemed that they had met in the hall, and the intruder was questioning the doctor, the doctor seemed to scream something about not letting anybody take his key, and suddenly the bands on his body no longer had numbers on them. Hope surged through Izuku as he focused.
Limbs he hadn't used in years pulsed with power, his adaptations giving him a stronger body than most grown men. He breathed in, flexing every muscle he could while straining against the bonds, every second stretched like eternity until the bonds finally bent in an ugly screech of metal.
Izuku grinned as he fell to his knees, a numb pain shooting through his knees as they hit the hard floor. Izuku breathed in and then stood on shaky legs as he thought one word.
'Freedom"
The word inspired strength into his limbs as he stumbled to the door, punching in the code he had memorized years ago in hopes of escape. He never realized he might actually get to use it. The door opened with a hiss, and Izuku could hardly believe his eyes as he finally could walk into the hall while not being chained to some damn table. He slowly gained speed as he jogged lightly through the halls towards the yelling voice of the doctor.
Anger was a familiar feeling Izuku thought had numbed over time. But it was flaring up and was getting hotter and hotter as he got closer to the voice. It burned into hatred as he rounded the corner and saw the back of the doctor. Ten feet away was a familiar shaggy man with long black hair wearing baggy black clothes and a long scarf his hair was standing up while his eyes glowed red. But Izuku's focus was on the doctor, who had just turned and grinned insanely.
"And look!! My Pandora's box is here! It knows its value to me! He will allow me to achieve Immortality!! HE IS MINE!"
Izukus body pulsed with fire as his face turned into a snarl.
'Target weight is 80lbs- center of gravity shifts forward towards my pelvis.'
Izuku felt the power of his quirk surge in a familiar tune as he felt his individual mass shift under his skin.
'Femur-to-tibia ratio: longer tibia equals longer strides, Tail for elongated for balance over high speeds and uneven terrain.'
Izuku was five feet away from the doctor, anger burning in his eyes as he felt each bone in his body shape and mold; a single mistake would spell disaster.
'Neural calibration, Rewrite locomotion to bipedal spring mechanics. Then allocate motor cortex priority to leg acceleration.'
He chanted the mental commands as he felt his face elongate and sharp teeth formed, matching his own snarl, and he watched in sick fascination as the joy in the doctor's face slowly turned to fear.
'Sensory filters enabled and modified, Motion tracking priority in vision overlapped by human processors for enhanced perception. Auditory range adjusted for high-frequency rustle detection.'
His body finished its transformation inches from the doctor as Izuku snapped forward his jaws around the bony neck of the doctor.
Aizawa
Aizawa was both confused and morbidly amazed. A naked child with fluffy green and black hair riddled with scars, who was walking like a newborn fawn, when he snarled, then his body shifted and transformed into a fucking dinosaur. Before he could react, the kid bit the neck of the doctor and, with a savage snap of its head, dislodged the head from the body in a spray of blood, but not as much as Aizawa was used to. The Dino Aizawa, now remembered as a Raptor spat out the blood and flesh in its mouth, then turned.
The Dino then transformed back into the kid that was vaguely foamier, and they stared at each other for a long minute. Then the kid spoke, still naked with unsteady legs.
"Y-you came?"
It was more a question as the kid took a hesitant step forward. And that's when he recognized the kid and connected the dots. He had saved the kid when he needed it, and all these years, he was probably hoping that he would be saved again. Why dream about a random hero to save you when there had already been a real one to save you?
"Yeah, kid. I did."
Aizawa said after a moment and caught the kid as he collapsed into his arms, holding him as he cried silent tears. Only then did Aizawa realize that the kid was as tall as him. And still naked.