AN: I do not own My Hero Academia

Izuku thought he knew what his quirk was. It wasn't anything amazing, just slightly enhanced physical capabilities. Everything pointed to this, so what was going on?

He was just walking home on his usual lonely route when a slime monster slid through the manhole nearby. Before he could even react, it had covered him, and started shoving the slime down his throat.

It was just a few agonizing seconds of pain before it started to change. The pain and panic of being unable to breathe left him as he started to breathe again. He thought a hero had come to save him, so he opened his eyes that had been screwed shut in the panic.

Only, no hero was there, the slime villain was still there, surrounding him, suffocating him. He instinctively shut his eyes and held his breath, only to realize that he could hold his breath. Why wasn't he being suffocated? He was clearly losing consciousness just a second ago, but now he could breathe totally fine.

The slime villain was freaking out, one second he had this kid in his grasp, as good as dead. All of a sudden he wasn't suffocating, and for every bit of slime forced down the kid's throat, even more was secreted from his body. He was making no progress at all, and that man would be here any second.

Realizing he was getting nowhere, the villain threw the kid away, and started to run on hastily formed slime legs. Before any distance could be crossed, a figure appeared in front of the villain. A ferocious wind blew out, spreading the slime into many small, nonthreatening bits.

Standing proudly was an extremely buff man in a stretched white tank top, and cargo pants. His eyes were shadowed over, and his blonde hair was reminiscent of bunny ears.

The man walked over to the kid who was lying on his back just a few feet away. "HEY, YOUNG MAN." He said in an overbearing voice. The boy on the ground shot up when he heard it.

"OHMAGOD IT'S ALL MIGHT!" He shouted with enthusiasm. Izuku started to speak at an unintelligible speed, losing breath all the while. Just a few tens of seconds of rambling later, and he took a large breath. His eyes lost the energetic feeling they were radiating before, and his heaving chest slowed down to a sedate pace.

The buff man looked down at the previously fanboying child, worrying that something had happened. Nothing that he could see was wrong.

"Wow! I can't believe I'm meeting you! You're my idol, and someone I wish to be like you someday." The boy said, much more calmly this time, though still excited.

All Might brushed off his confusion and finally spoke. "HAHA, WELL YOU'LL JUST HAVE TO TRY AS HARD AS YOU CAN FOR THAT DAY TO COME. LUCKILY THAT VILLAIN DIDN'T ATTACK YOU, AND YOU'RE ALRIGHT." Said All Might in his usual voice.

Izuku seemed to gain sparkles in his eyes, "Actually, um... well, nevermind, I'm Izuku Midoriya. More importantly, can you sign this!?" He shouted. In his hands, there was a notebook titled 'Hero Analysis for the Future'.

All Might took the book, skimming through its contents before finding a suitable place to sign. Handing the book back, he said, "YOU'VE GOT QUITE AN EYE FOR DETAIL YOUNG MAN, NOTICING SUBTLE CHANGES WILL HELP YOU IF YOU DREAM TO BECOME A HERO. I'M SURE YOU'LL BE A GREAT HERO ONE DAY. NOW, I HAVE TO GET GOING."

All Might squatted down in preparation, inserting two bottle full of slime that Izuku hadn't even seen him fill up into his back pocket. Izuku thought of what All Might had said, and latched onto his pants just as he propelled off the ground.

Izuku began to scream as air filled his lungs dangerously fast mid-flight. Strangely enough, only a few seconds later, and he was able to breathe fine even with all the excess air. His eyes that started to become dry were suddenly normal, and he could see with all the wind just as he would without wind. All Might had noticed him, and shouted something he couldn't make out over the winds blowing by.

Soon, they had landed on a building. Izuku was expecting to be heaving as they hit the ground, but he was in perfect condition. He brushed off his confusion and looked toward his idol. In All Might's place was a cloud of smoke.

As the smoke cleared, Izuku saw the figure inside of it. It was a dangerously skinny man with blonde hair. He started to freak out, "GAH, YOU WERE AN IMPOSTER!" he yelled toward the man. Ten seconds later, and Izuku had calmed down again, surprisingly fast.

"No, this is just what I really look like." said the man. Izuku stopped and thought about it. It really wouldn't make sense. After all, there was no denying his power, there would be no need to impersonate All Might. Unless he was a villain, but he took out the slime villain. It's unlikely a villain would chase another villain for so long, just to turn him in.

"You're taking this surprisingly well." He said, causing Izuku to stop and think once again. He was right. Normally, in a situation like this, he would have expected himself to panic. That wasn't the case, he was being rather rational and calm right now. Not that he wasn't feeling anything, but he just felt much more in control of his emotions.

"Yeah, I don't know why." Said Izuku in a steady voice that came off as more confident than he had ever felt. He scratched his head, confused about what was happening, but shrugged it off when he saw All Might spit up blood.

"Oh my god! All Might, are you okay!?" He asked as he ran to the Pro Hero. He was stopped at arms length by All Might.

"Don't worry kid, this is because of an old injury from a few years ago, nothing new." He said as he pulled up his shirt, revealing a caved in chest.

"Because of this, I can only be the ALL MIGHT that you know for around three hours a day." He said, transforming as he said his hero name.

"Wow, what happened?" Asked Izuku in a sad tone. Knowing that his idol was suffering because of an injury really put a damper on the excitement of meeting him.

"It's from around five years ago, the public doesn't know about the battle I got it from." They sat in a solemn silence for a few second before Izuku spoke up again.

"Do you really think I can be a hero like you? Most people don't believe in me, because my quirk is so simple. I want to be a great hero like you in the future, someone who saves people with a smile. However, my quirk can be boiled down to slight regeneration. So what? I could be the hero who never gets sick? I want to be better than that. Someone like you, whose existence alone stops villains from appearing."

All Might looked at the young boy who had just poured his feelings out. He could tell from the look in the boy's eyes that he was fearful of being denied this. He could so easily crush this boy's dreams with just a few words. That terrified him. He never wants to hurt someone like that.

"No worries my boy. If your quirk is regeneration, then use your wit and attention to detail, and exploit that ability to the fullest. I saw some of what you had in that notebook, you've noticed some things about other people's' quirks that I'm sure they themselves hadn't noticed. That's a skill you can brag about, so use it to your fullest advantage."

Izuku smiled up at the man who believed in him more than anyone else had. This was all he needed, he just had to have someone else who believed in him besides himself. He could become a great hero. He would become a great hero.

Just as he was about to speak again, an explosion was heard from just a few blocks away. A cloud of dust arose from the area it came from.

"AH, All Might, it looks like something is going on over there, you should go help."

"... Sorry kid, but I'm out of time for today. There are other heroes to deal with it."

Izuku's face went a little red at having forgotten that All Might was now on a time limit. "Sorry, I forgot. I'm gonna go check out what's happening. Bye, All Might!" Before All Might could say anything, Izuku had run into the stairwell.

…

Izuku jogged up to the alley where the commotion was taking place. At a glance, he saw many heroes he recognized, including Kamui Woods, and Mount Lady.

He could hear the people standing around talking about the progress of the fight. Apparently, it wasn't going so well, and a kid was taken as a hostage!

He ran to the front of the crowd so he could get a look at what was happening. Izuku saw the very same slime villain that had attacked him earlier. Inside of it, in the same position that he had been in, was a figure.

Izuku's eyes widened as they recognized the person in the slime. Before he knew it, he was moving towards the slime at a fast speed, putting everything he had into the pumping of his legs. Before he knew it, he was right in front of the villain.

That's also when he realized he didn't have a plan.

Acting in desperation, he threw his school bag into its face. Before it could even reach the slime, a large explosion blew both it and Izuku away. Izuku was able to protect his face with his arms, but now both his arms were singed.

He shook off the pain, and took advantage of all the dust and rubble that had flown into the air. Running forward through the cloud, he jumped up in the air as soon as he could reach the slime.

Using the force from falling into it, Izuku shoved his hand into the slime, searching for the person inside. His hand tore through the viscous substance with surprising ease. It tunneled right through until he came in contact with the blonde haired boy on the inside. Grasping onto the boy's arm firmly, Izuku yanked him out of the slime.

They both fell onto the ground, leaving themselves totally vulnerable. The slime took advantage of this and proceeded to surge forward in an attempt to recapture its hostage. Before it could make any headway, a buff figure that Izuku recognized appeared.

"TEXAS SMAAAAASSSHHHHHHH" Yelled All Might as the winds from his punch alone disintegrated the villain. The force even caused it to rain, showcasing just how immense the strength of that punch was.

Before Izuku could acknowledge what was going on around him, he was surrounded by the media. He looked around for All Might, wanting to thank him for saving him once again. He took all the reprimands from the heroes in stride, more thrown off by the glare coming his way from the boy he had saved.

Katsuki Bakugou, otherwise known as Kacchan to Izuku. They were childhood friends, and used to hang out together all the time. This changed when their quirks started developing. Katsuki would lord his powerful quirk over everyone he knew, and thought he was too special to be friends with anyone weak.

Izuku was weak in the eyes of Katsuki, so he wasn't treated as a friend. This caused the two to slowly drift apart. Katsuki didn't want to associate with someone weak, and Izuku didn't want to associate with a bully.

Now, their relationship was just a few rare confrontations where Katsuki would verbally abuse Izuku. Izuku had learned to ignore it for the most part, the snide comments about how he couldn't become a hero. He just silently built up his determination.

….

When the media finally let him go, Izuku walked home with his head down, pondering over the events of his day. Meeting All Might, the slime villain, meeting All Might, Katsuki, meeting All Might, and his quirk.

His quirk. He thought it was just slightly increased regeneration. He never got a cold, never bruised, and was slightly more buff than he should be. There wasn't really anything that pointed away from that.

Izuku furrowed his eyebrows as he thought of what could be odd about his quirk. A breeze blew by, ruffling Izuku's clothes. His eyes widened as he realized something. He's never really been cold, or hot for that matter. Of course, he always wore the appropriate clothes for whatever weather, but he has never needed to huddle up in a blanket during a cold winter night.

How that also give him the ability to breathe through that slime villain, or tear right through it? Izuku thought back on how he was also suddenly calming down, it was all so confusing to him.

He continued to walk home, silently pondering over his quirk.

"HEY, Deku!" yelled a voice behind Izuku, snapping him back to reality. He turned around to see Katsuki standing there, looking slightly out of breath.

"Hi, Kacchan." replied Izuku unenthusiastically.

"I didn't need your help, so don't go thinking you're better than me with your weak-ass quirk." Said Katsuki, walking up to Izuku and placing a hand on his shoulder, so that he could threateningly look him in the eye. It wasn't very effective, and Izuku just averted his eyes slightly downward when he met the stare. He didn't want to antagonize anybody.

Katsuki growled as he saw Izuku look away. He narrowed his eyes, and with a grunt created a small explosion with his right hand that was on Izuku's shoulder.

Katsuki was prepared for a scream of pain, and a charred shoulder. When he relaxed his grip, and removed his hand, the only thing wrong with the green-haired boy's shoulder was the missing fabric around it. What should be burnt skin, was instead smooth and unblemished.

Katsuki grunted as he saw this, "So, your quirk is better than I thought, but you're still nothing compared to me." With a final harrumph, Katsuki turned away from Izuku and left.

Izuku looked down at his shoulder, absentmindedly rubbing a hand over the untouched skin of his shoulder. An idea began to form. His quirk may turn out to be more impressive than he could've ever thought.

As he stood there, ruminating over the possibilities his quirk could have, a form landed on the ground in front of him. Izuku's head snapped up, wondering if Katsuki had come back, and had decided to put on a display of power.

Instead, he saw All Might in his regular form. The number one hero walked up to him.

"All Might!"

"SSSHHHHH, don't call me that where others can hear, I don't want to cause a scene. Call me Mr. Yagi instead." Said All Might, frantically checking the surroundings for any sign of people.

"Oh, got it, Mr. Yagi. What are you doing here? I thought the press would be attacking you by now."

"HAH, if I hadn't learned how to escape the press a long time ago, people would know my real name by now. As for what I'm doing here, I wanted to ask you, do you truly want to become a great hero?"

"OF COURSE!" Answered Izuku immediately, barely letting All Might finish the question.

"Then, how would you like to have my quirk?"

"Wh-what!?" Izuku exclaimed in shock. Have someone else's quirk? Was that even possible?

"It's something special to the quirk I have, I'm it's eighth user."

Izuku sat in silence, thinking about the possibilities of such a quirk. When he thought about how strong he could get with it. He shook with excitement as he imagined himself as a miniature All Might. This would show Katsuki that he wasn't weak.

But… would that really prove Katsuki wrong? It would make him strong, no doubt, but Katsuki always went on about his weak quirk. That's where Izuku wanted to prove Katsuki wrong.

His quirk wasn't weak. Now that he knew about it, Izuku would do just as All Might said. He would exploit the abilities of his quirk as best as he could. One day, he could become stronger than All Might.

Yes, he didn't need someone else's quirk to become powerful. He would do so with his own abilities.

"So, what do you say?" Asked All Might in anticipation, thinking he had found the perfect successor.

Izuku smiled toward the skinny man. "Sorry All M- Mr. Yagi, but I want to become strong with my own power. After today, I know I can do it." He said, clenching his fist in determination.

"... No need to apologize, Young Midoriya. Your determination is inspiring. It's something you need to be a bigger man to deny, I know it's something I couldn't do. You're an incredible kid. I hope we get to see each other in about… let's say ten months." Laughed All Might as he transformed and disappeared.

Izuku wondered what that was about, why ten months? However, his thoughts were soon once again consumed with the possibilities of his quirk. He ran home, barely able to contain himself as he thought of how he would test his quirk.

When he got home, his mother was there to scold him for his involvement in the slime villain incident. After the scolding, of course, came the fountain of tears. For perhaps the first time, Izuku's mother, Inko, was the only one crying.

Izuku was still thinking about his quirk, but he couldn't bear to see his mother cry. He waited until she had cried herself to sleep. After placing her on the couch, Izuku got to work.

He started with something that would undeniably prove or disprove his theory. Going to the kitchen, he found a sharp knife.

Bracing himself, Izuku held the edge of the knife over his left palm. Deciding to just go for it, Izuku held his breath and sliced.

Some blood leaked out from the relatively deep incision on his palm. Izuku stared for a minute as the wound closed, biting the inside of his cheek to help with the pain.

It was just a show of quick regeneration, but the next part would be more important. Izuku once again place the edge of the knife in his palm. Barely hesitating, he sliced once more. He had to push harder than he had the time before to get a cut.

This time, he only had to stare at the cut for a few seconds before it was gone. Only a few drops of got out this time.

He was right, his quirk wasn't just regeneration. Deciding to try one more time for confirmation, Izuku went to cut his hand again, this time without any hesitation whatsoever.

Izuku felt resistance when he tried to slice his palm this time. He couldn't even break through his skin. After trying for a minute to cut his hand again, Izuku realized that his skin would not be pierced by the knife no matter what.

Even trying to slam the point into his hand didn't work. It felt like the knife would give out sooner than his skin would.

Izuku grinned as he stared at his blood stained hand. This was his quirk. He could become strong using his own quirk.

Thinking of something else he could do, Izuku drew himself a bath. After getting in and relaxing, he dunked his head under the water.

He had to force himself to try and breathe once he was under. As soon as he did though, he found he could breathe just as if he was above water. He didn't have to wait any time at all for it to kick in. He had never opened his mouth under water before, so there had to be a reason for it.

Perhaps the incident with the slime extended to water as well. Or maybe just drinking water was enough? Izuku wasn't sure, and figured he could test with other things at another time. For now, he relished in the feeling of breathing underwater.

Izuku took a long, indulgent bath, making a mental list of things to allow his body to adapt to. There were 10 months until the UA entrance exam. In that time, he would make sure to make himself as invincible as he could.

AN: This is my second story. If you've read my other one, you probably realize that I like to base my stories around the quirk that I give Izuku. In this one, Izuku's quirk is Adaptability (If you can't tell by the title). It's based off a villain from a book series I read about a year ago. It's called the Quantum Prophecies series (Check it out, it's pretty interesting), and has two of my favorite book villains. The villain basically has a power where, if he is shot with a gun, the first time will hurt, and the second time the bullet will just bounce off his skin. He is also a few hundred years old, so he's experienced enough to be pretty all powerful. The ability even extends to simple things. For example, if someone picks him up to fly him somewhere, they can do so the first time. However, the next time, if the villain so wished, they would be totally unable to pick him up.

I think this ability works very well in a world where superpowers exist, as it means Izuku won't become OP immediately.

I don't know how frequently I'll update this. The only reason I even wrote it was because of the 5 day weekend I had off from school.