If Izuku had a...

Blood Regeneration Quirk

Warning: Gore, not too graphic but it's there.

Quirk rundown: Basically, Midoriya has black blood that can heal his wounds, it would seep out his wounds to fill it in and heal. For example, his black blood would fill in an open stab wound and heal it, the same goes for a missing body part. Detached body parts will eventually turn into congeal blood before rotting. It is a lot easier and faster to heal by returning the blood to him than having to produce more at a slow rate. I hope that explains it.

It was a pretty bloody sight, there were bits of flesh speckled everywhere and blood smeared across the pavement. The entire intersection was a complete wreck with it being littered with sharp bone fragments and every window was smashed. The Sidekick standing near Aizawa looked like he was going to empty his stomach on the spot, the insomniac hero scooted away from him.

The policewoman nearby seemed to be dealing with the situation much better than the sidekick, she walked over holding a clipboard and pen, "Eraserhead" she acknowledges.

Aizawa nodded, he went straight to the point, "What did they do this time?"

"Other than destroying an entire intersection? They try to intercept a burglary, the villains' quirks being spiny needles, claws, and werewolf. All three are in custody. The boy, Midoriya was found critically injured but insisted that he didn't need help and that he would just regenerate"

Aizawa massaged his temple, 'Of course, it had something to do with that problem child' The bits of flesh that remained on the crime scene slowly broke down and turn into a black liquid, the blood on the pavement follow suit and began to coagulate.

The hero cringed when the sidekick started retching out his lunch, 'I don't have enough sleep to deal with this' Aizawa pointed at the bloody pavement, "Get someone to scrape that off. Put it in a bag or something and give it to Midoriya"

The policewoman nodded and guided him to the police station where his students were being held. Aizawa was greeted with the sight of Todoroki, Bakugou, Iida, and Uraraka lounging around with a cup of coffee in hand provided by the police station.

And then there was Midoriya, sitting on the couch while taking small sips from his cup, his entire right leg missing, what was left was a bloody stump with the shattered thigh bone sticking out. Nobody seems fazed by the fact that Midoriya was casually bleeding on the couch.

Aizawa raised a brow, "Where's your leg?"

"Well, you see...a villain was about to attack Uraraka from behind Sooo... I kind of jumped in the way and took the hit"

"Thank you, Deku, really"

"...The villain ended up ripping off my leg and when I try to reach for it, Iida accidentally kicked it to the other side of the street..."

"My apologies, Midoriya, I didn't mean to kick it away from you!"

"...I tried to get there as fast as I can with only one leg but a villain was standing over my leg so Todoroki froze them along with it..."

"Sorry"

"...And after that, Bakugo tried to blow up the villain and ended up blowing up my leg into pieces"

"Not sorry"

A policeman who was unfortunate enough to end up with cleaning duty walks into the room with his arms extended out holding a plastic bag, "For Midoriya?"

"Hey, my leg, thanks!" Midoriya takes the bag from the outstretched hand. The policeman cringed at the sound of sloshing coming from the bag and went green at the sight of Midoriya casually opening the bag and dumping out its contents onto his lap.

The effects weren't immediate. The congeal black blood sitting on his lap eventually started to merge with his leg, starting at the stump before regenerating down to his toes in under five minutes. The policeman had long left the room as he tries to hold down his stomach contents. 

A heavy silence settles over the room, the UA students turn to stare at their teacher as they waited for his final verdict. Aizawa scans his students with intense scrutiny, his gaze particularly lingering on Midoriya's newly formed leg and the barely noticeable black spots splattered on all of them 

"You're all grounded"

AN: Yep, It's official, Aizawa adopted a classroom worth of children