A/N: This jumps around a lot since this is basically a preview, as I state at the end, for an idea I came up with.. Also, it's really long. And, uh.. IzuRoki is a cute ship name I came up with for the two. And this is by no means what the actual story will be like but it will at he same time and- uuugh. There will be very different aspects so even if you read this there's not really any spoilers for my story. Also, this is terrible. So, uh, basically? It's a trash post you should not read unless you want to read a trashy Catzuku Quirk one shot until the book comes out.

Midoriya Izuku was cowering in the playground, dark green, almost black, ears and tail waving, hiding from playground. He loved his quirk but everyone made fun of him for it so he always hid it. Everyone told him it was a useless quirk so he might as well be Quirkless. Later that day, he became just that, though he wouldn't remember ever having a quirk.

Five years later and he was standing in front of a disheveled All Might who looked like a skeleton. "Uh, sir?" Izuku asked, his feet shuffling anxiously. "Is, is there any way for me to be a hero? I, I don't have a quirk." He mumbled, hopeful, his amnesia from having his head slammed into a metal pole by an explosion when he was ten was still not cured and never would be. His hero furrowed his eyebrows, thinking. "It would be dangerous," he started slowly. Izuku's face fell, expecting the same response that he always got. "But not impossible. If you had the right equipment and traits, it might work." All Might whispered. Izuku's eyes lit up.

|~~|

Izuku was happily walking along when he noticed a crowd and the sound of screaming. He ran forward, shoving his way to the front of the crowd. The sludge villain was here with a group of heroes surrounding it, just standing there. "What are they doing?" He thought to himself, staring. Then he heard a familiar shout and an explosion and his eyes shot wide open. "Kacchan!" He screamed, feeling something happen but he looked around and at himself and saw nothing out of the ordinary, just small white stubs on his fingers that he assumed were his nails.

He vaulted over the protective barrier, sliding his backpack off his shoulder and into his hand. "Let go of him!" He yelled at the villain, throwing his backpack at the villain's eye. He figured it was the only thing not made of sludge and targeted it. It turns out he was right as the villain flinched and Izuku ran towards it. He started frantically clawing at the villain, allowing Bakugo to take a breath, but he was pulled away. He looked up in time to see All Might appear and take care of the villain. Izuku was about to pass out when he was woken up rudely by Bakugo yelling in his face with the familiar sound of a sparking explosion in his ear.

Izuku sprang back, flipping in the air and landing on his feet, catlike. He stared at his childhood friend (bully) and he stared back. "The hell was that, Deku?!" Bakugo screeched, an actual explosion occurring. "I- I was trying to h-" Izuku was cut off by a loud hacking noise and he continued to cough, doubling over. Bakugo's eyes widened, this had happened before. "Quick! Someone get a medic!" Bakugo yelled, eyes turning frantic quickly. When Izuku was panicked sometimes he would start convulsing and hacking up blood. It always freaked Bakugo out and concerned the ash blond teen when it happened and he hated it. Heroes rushed over, probably to scold him, and then they saw what was happening.

Izuku was curled up in a ball, hacking, small droplets of crimson flying out of his mouth with each cough. All Might was faintly reminded of his own condition which caused a whole flurry of panic. Izuku was quickly loaded onto a stretcher and taken to the hospital, accompanied by his bully/friend. (Kacchan really was both- sometimes he was a jerk, hitting and blowing up Izuku, and other times super caring and nice.)

|~~|

The nurse was writing on a clipboard, asking Katsuki about Izuku. "What's your relationship with him?" "Childhood friend." "What's his quirk?" "Doesn't have one." "Parents?" "Midoriya Inko." "His Name?" "Midoriya Izuku." "Your name?" "Bakugo Katsuki." Bakugo normally hated this but he was so concerned for the one person who always stuck with him that he answered mechanically. "Age?" "14." Katsuki was numb. Completely and utterly numb. Did he cause it this time? Did he cause it the previous times? He didn't know what caused them. Just that they started happening after Izuku lost his quirk because of him.

Katsuki remembered the event when Izuku lost his quirk. He was mad at Izuku and hadn't seen the pole behind him. He caused an explosion that sent Izuku recoiling, his head slamming into a pole. Bakugo watched, horrified, as Izuku's eyes rolled backwards and he slumped down. Blood was covering the ground, pooling beneath the ten-year old. Katsuki started screaming, pulling out his kid phone and called 119, jumbled words falling out of his mouth but apparently the operators understood enough to send an ambulance. The next day, when Bakugo asked about Izuku and if he was okay and why Izuku didn't have his ears and tail out, the green-haired boy stared at him. "What? I'm Quirkless, remember?"

|~~|

Izuku eyes were heavy and he didn't want to open them. But he heard voices, one of them he was pretty sure was Bakugo's, which caused extreme amounts of surprise. He forced his eyelids up, surveying the room. "Can I have water?" He mumbled, voice cracking and throat dry. People immediately started rushing around and he held up a hand. "I-it's Okay!" He says, coughing again. "It happens a lot!" He finishes, smiling softly. Everyone stops in their tracks. And they all slowly look at him. Izuku suddenly had a feeling he did something wrong. "Is.. is something wrong?" He choked up, eyes wide. "How long...?" One of the doctors asked with wide eyes. "Uh, five years. Since... Uh.." he glanced at Bakugo who wouldn't meet his eyes. Izuku swallowed, a lump in his throat. "I don't actually know. One day I woke up in the hospital when I was ten with major head injuries." He looked away, not meeting anyone's eyes.

A knock echoed through the silence. The door was opened and his mother rushed in, tears falling as waterfalls from her eyes. "Izuku! My baby!" She cried, rushing to him. She doesn't hug him, knowing how fragile he is, but stands by his bed restraining every urge to hug him. Her arms tremble and Izuku hugs her gently and she immediately hugs back, just as gently.

   A few hours later, All Might in his skeletal form strolled through the door. "Hello, young Midoriya." He smiled at the bed-ridden teen but his expression quickly slipped away into one full of concern. "Are you alright?" All Might asked then quickly shook his head. "Of course not, you're in a hospital." The blond sighed, his deep set eyes somehow still conveying emotions. Izuku looked up at All Might, blinking slowly. "What do you want?" He asked tiredly, yawning. All Might noticed that a lot of the young male's actions were cat-like including his yawns, apparently. He shook the thought off and offered the dark-green haired boy something that Izuku knew he wouldn't refuse. "You mentioned you were Quirkless when we last met and that you wanted to be a hero. I have a proposition for you," All Might swallowed, nervous, blood pooling in his mouth. "I, Uh, was wondering if you'd like to train with me? Then I could help you become a hero." The Symbol of Peace looked at Izuku, nervous. The teenager's eyes were wide and a smile broke out across his face. "Yes! Of course!"

|~~|

Ten months later and a clean beach that was previously covered in trash, Izuku was noticeably stronger. His birthday also passed, making him 15, and he was now standing in front of All Might. "Young Midoriya," the number one hero began, "Good job on cleaning the beach, and you now have a much higher chance of getting into U.A.!" All Might exclaimed. Izuku beamed, hearing that he had a chance of getting into his dream school to be a hero was.. amazing. "And I have one more thing for you, if you will accept it." Izuku looked at his idol, confused, and All Might smiled. "My Quirk is called One For All. I can pass it down to my successor. It is a stockpiling quirk and you, my boy, will be it's ninth owner if you accept." Izuku's eyes were wide with shock. "Of course, sir!" Izuku managed to choke out with glee. All Might beamed. "My name is Toshinori Yagi, young Midoriya. You deserve to know it since you are my successor." All Might smiled at Izuku again and plucked out a hair from his head. He offered his hair to Izuku. "Eat this."

Izuku stared at him. "Uh, What? Okay..?" He cautiously placed the hair in his mouth and swallowed it. "Why did I need to do that?" Midoriya asked, shuddering. "One for All is passed down by DNA, so it was either that or drinking my blood." Yagi told him. Izuku shrugged; it wasn't the weirdest quirk around. "Be very careful when using it." All Might tells him. "It will break your bones if used incorrectly." Izuku's eyes widened with horror. "The entrance exam is tomorrow!" He squeaked. All Might nodded grimly. "Indeed. It will have activated by then. Be safe, my boy." Izuku gulped but was smiling. "Yes, sir!" Izuku called, smiling.

|~~|
During the practical exam

He stared at the huge, no-pointer robot. Uraraka, who he had met earlier when she saved him from falling flat on his face, was stuck under rock with a huge robot looming over her. It was called the Arena Trap and they were told not to engage it. 'But he couldn't just leave her!' Izuku mused. He finally decided to screw it all and save her.

    Izuku's eyes narrowed as he bent his legs and felt them sizzle with One for All and he leapt up and charged his hand with power. He pulled his hand back and punched the robot. Its face promptly crumbled into itself and the bot fell over, but Izuku had a new problem.

He couldn't move his legs.

   The boy just kept falling, sighing, admitting to the fact that he was probably going to die. But right before he hit the ground, Uraraka hit him. He stopped and hovered above the ground from her Anti-Gravity quirk and she released him. She promptly hurled rainbows, strangely enough, and both of them lay on the ground, stunned. "Time!" Present Mic, one of the pro heroes, called out. Izuku blearily realized he hadn't gotten any points before passing out from pain. His arm and legs were completely shattered, anyways.

|~~|

At USJ (A/N this was my favorite part of this trashy one shot to write so far)

  Dark swirls of purple appeared in the air, villains stepping out of them. Izuku and everyone else there watched in horror as tens of villains flooded out of the portals. Then the last three appeared- a strange, huge, black, towering mass of muscle with a bird face and an exposed brain. It was the last thing he saw before being warped away to a ship with Tsuyu and Mineta.

    He glanced at his classmates helplessly, Mineta holding two of the purple spheres he produced from his head in his hands. Tsuyu was looking around, frowning, as water villains swam up to them. Tsuyu turned to Midoriya, whispering, "They obviously don't know our quirks, ribbit. If they did, they wouldn't of put me here. Ribbit." Izuku looked at the girl with the frog quirk, nodding slowly. "True... but we have to get down there and get out of here!" He exclaimed, staring down the villains. He felt warmth spread over his back but paid it no mind, assuming he was just, well, hot. He also felt many stares directed at him which made him curious but he didn't question it.

   "The hell? Is that green haired boy growing fur?" One of the villains asked, eyebrows raised. Izuku's eyes widened but he decided that that was not important right now that he apparently just developed a quirk and he would explore it. He swallowed his nerves and leapt straight into the water, having always loved swimming. Tsuyu and Mineta followed, and the trio quickly knocked the villains out and escaped, Tsuyu wrapping her long tongue around them and leaping away with, as you probably guessed, frog-like dexterity.

   They ended up at the main plaza and watched with horror as the bird-like tower of muscle, apparently called Nomu, smashed their teacher's head into the ground. Aizawa, better known as Underground Hero: Eraserhead, was unconscious. Deku felt something burn on his head and lower back and suddenly felt the addition of extra appendages to his body. His vision and hearing sharpened, pupils narrowing to cat-like slits, and he briefly touched his head to feel low, rounded, soft ears and he lashed a 25 inch long tail. His teeth sharpened and canines turned to fangs, black fur rippled across his body. His classmates were busy fighting but the loud yowl from Midoriya's direction froze everything. Claws were sharp and slightly curled at the end of the boy's hands which quickly turned to paws. Then black fur surrounded the area and when it settled, a large, almost solid black colored jaguar stood in Midoriya's place. It had a dark green tint and the faint design of his outfit in its fur and the big cat was not happy. It took everyone a second to realize this was Midoriya, including himself, but he didn't care. He lashed his tail once more and sprang.

   He assumed the exposed brain was the weakest point so that's where he aimed. His powerful feline body gathered its muscles and, with claws unsheathed and paws outstretched, the boy sank his teeth and claws into the Nomu's arm, missing his mark. The creature didn't even react which obviously angered the cat. The black panther (A/N I actually researched a little and black panthers can be jaguars or leopards, or any of the big cats with solid black coats. Anything I say about Izuku's cat form has been researched at least a little bit.) climbed up the Nomu, hissing since his mouth was free. His jaws that bit down with as much strength as he could muster, the jaws of a Jaguar being the second strongest of all mammals, sank into the Nomu's brain. His claws anchored him to the body and many were shocked by the viciousness of the kind boy. He shook his head from side to side, occasionally pulling a paw up and tearing into the brain even more. The Nomu couldn't move, it's brain too damaged. Brains flew from the powerful jaws, blood soaking his maw hardly visible against the dark coat. All Might burst into the room just as the Nomu started to fall forwards, the jaguar on top of it still tearing him apart, even though there was hardly any brain left. One of the students had pulled Aizawa out of the way a few minutes ago, still horrified by the sight of blood and brains flying from Midoriya's feline form's mouth.

   The cat noticed All Might quickly and gracefully leapt off the Nomu's back; the Nomu quickly fell down and Shigaraki was staring in awe and horror at the black panther. All Might looked at Izuku, confused, and the boy shifted back to his human form. His clothes, which had apparently transformed into fur as well, stayed on him, much to everyone's relief. The blood and brains surrounding his mouth and in between his fingers was a disturbing sight to say the least and quite annoyed the boy. He frowned and slowly shifted back into panther form and started washing himself, some strange, forgotten instinct taking over. His rough tongue lapped at the blood on his paws, cleaning it, and proceeded to wash his mouth with said paws. He finished washing himself under the surprised looks of hose present and conscious, and shifted back to human. The blood and brains were thankfully gone but then the boy noticed the looks.

   Then what he had done set in. "Holy crap I have a," he caught himself and fumbled, "another Quirk!" Were the first words that flew out of his mouth without his proper consent. All Might blinked, shocked, and Katsuki was staring. "Y-your old Q-quirk," He stammered, backpedaling quickly. "Y-you got it back." Izuku stared at him. "K-Kacchan? What do you mean? I- I didn't have a quirk besides my strength one." Katsuki swallowed. "I-I know that you're a late bloomer, Izuku, but that wasn't the case originally." No one interrupted him as Aizawa was already taken away and was being healed. Everyone could sense this was important. "Y-you had a quirk that allowed you to turn into a black panther or only show your ears and tail or do neither. A-and you never showed anyone but me because I was here when it developed a-and when you lost it." Katsuki swallowed, shuddering. "I s-saw someone slam your head into a pole when we were ten. A-and there was blood everywhere a-and I called an ambulance and they said you wouldn't remember anything about your Quirk, or even having it. They said you were effectively Quirkless then." Katsuki finished his explanation to the shocked faces of classmates and heroes alike, and promptly fled. Izuku sat there, contemplating.

|~~|

Izuku was sitting in front of Recovery Girl, Nezu, a half-recovered Aizawa who was there because they were in the infirmary, and a skeletal All Might. "I... I don't know what happened. I just saw Aizawa-Sensei laying there, his scarf and hair," he looked at the long black hair in question and shuddered, "splayed on the ground, blood slowly pooling and I was overcome with... rage? I don't really know." Izuku swallowed and glanced around. He shifted nervously. "Then I felt a warmth on my head and lower back and a tail and cat ears appeared, apparently. Claws formed and my vision and hearing sharpened then there was fur and then I was a panther," Izuku rushed his words, getting them out quickly. Nezu nodded slowly.

"Can you show us? So we can take measurements?" The Principal asked, his paws clasped. The mouse looked at Izuku who nibbled on his bottom lip. "I... I can try." He looked over at All Might. "Is.. is this okay? That I have my Quirk and the other one?" He asked his hero nervously. All Might nodded, smiling softly. "Of course." Midoriya beamed and then sighed. "This will only be my second- er, third time that I can remember." Nezu and Recovery Girl looked at him, confused. "W-well," Izuku started, explaining what Katsuki had told him. They were both silent when he was done. "I, um, am going to shift? Now?" Izuku said, voice questioning.

He closed his eyes and tried to recreate the warmth he felt in the same places. All he managed to do was to turn his hair black temporarily. Izuku sighed, opening his eyes, and saw the four adults staring at him. "What?" He asked. "You're.. hair... is black." Aizawa muttered. Izuku shrieked relatively quietly, knowing people were resting, and his hair immediately reverted back to its natural forest green color. He felt embarrassment flood his face and two cat ears poked out of his head. He noticed more staring and shuffled nervously. "You did it, young Midoriya!" All Might exclaimed. Midoriya perked up, a long tail snapping out behind him. He reached up with his left hand and patted his ears, smiling. "Uhm, So, should I try turning into a full on black panther or...?" Recovery Girl nodded. "It would help us significantly because that means we could determine whether you're a leopard or a jaguar. While jaguars are normally in South America some do exist in Japan so we will take it into an account." Izuku nodded. This part he remembered relatively well.

Izuku's eyesight sharpened and sleek fur rippled across his body. His white shirt that said 't-shirt' on it became a part of his pattern, a lighter patch covering him like a t-shirt and darker lettering spelling it out. He also had a faint outline of the jeans he was wearing present. Claws quickly formed from the tips of his finger and nails, his tail lashing. An explosion of fur and Recovery Girl's groan accompanied the last part of Izuku's transformation; the fur settled and a sleek black panther stood there proudly.

A loud meow fell from his mouth, a few people waking up. Aizawa smiled very slightly, deciding that Midoriya was his favorite student now. Eraserhead might have a slight bias to black cats. Todoroki somehow sensed that there was suddenly a cat because he just appeared in the doorway. His eyes lit up very slightly when he saw the majestic feline sitting in the room. Izuku was surprised to see the reaction; Todoroki never showed emotion in his experience. A few minutes later most of class 1-A had come to see if they were able to pet the panther. Recovery Girl shooed them all out pretty quickly since Izuku was hiding behind Nezu, funnily enough.

Recovery Girl quickly measured and took notes on Izuku who had stood up and determined that he was a jaguar, which meant he had an extremely powerful bite. They were all confused on why this was his quirk when his mother and father had nothing to do with animals or shifters. It was later discovered that he had a shifter in his family two generations back on his father's side.

|~~|

Shoto Todoroki's fight with Izuku was inspiring. The One for All holder had shouted at him, "It's your power! Not his!" Regarding his fire half, causing Shoto to promptly burst into flames and the fight to heat up, literally and figuratively. Izuku grinned, his smile showing fangs, before and explosion of fur occurred. Bystanders yelled in shock, having seen his Quirk earlier on as strength augmentation with a heavy drawback and he hadn't used either of his quirks in the first two challenges, much to everyone's frustration. Then their attention was snapped to the large panther that sprang from the puff of fur. Todoroki recovered quickly- he would never get used to Izuku's dramatic transformation- and ice rushed forwards to greet the panther. The cat twisted, landing on its paws to the side of the huge iceberg. Midoriya had trained his Quirk as much as possible since USJ, spending at least two hours on just transforming and basic maneuvers each day.

Izuku hissed and showed his fangs to Todoroki, ears pressed flat against his head. He bounded up the ice, climbing it, his instincts guiding him and sharp claws sinking into the slippery ice. He leapt off the ice tower and twisted before hooking his paws with sheathed claws into Todoroki's shirt; he didn't want to hurt him too badly. The "Half Hot Half Cold" Quirk holder was knocked over, causing  him to wrinkle his nose and knock the cat off of him with a well aimed blast of ice to the nose and paws. Izuku yelped and sprang off of Todoroki when he felt heat under his paw and cold on his sensitive pads and nose. Todorki seized his chance and pushed the cat out of the arena while he was midair.

Izuku landed on his side, stunned. After a minute or so, he got up and transformed in another puff of fur and walked over to his opponent, smiling. "Good match, Todorki-kun." Shoto nodded, his dual colored hair shaking and already messy. The red and white hair was ruffled by the panther shifter who had to get on his tiptoes to achieve the small, friendly action on the taller boy. Izuku smiled, shaking his head, and Todoroki along everyone else noticed the tail and ears that formed after the small action. The dual quirk user had to fight back the urge to pay the ears and instead smiled very, very slightly at Izuku who grinned even bigger at him. At the point Todoroki's eyebrow twitched from restrained amusement and the two walked off the field, chatting, Todoroki helping the shifter get to Recovery Girl because of Izuku's injured limbs from landing on his legs wrong, much to Todoroki's horror.

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Hope you enjoyed that mini summary because I've decided that, after a week of writing this and being thoroughly unsatisfied, to make this a story! So this is basically a preview up to that point I've shown. Hope you enjoyed!

   -Fire (and her siblings...)