Sound part 1 [My Hero Academia AU] [Discontinued]

Prologue

Despite being half-blind I've always been able to see, better than most people as well. I guess its because of my quirk, no matter how small the sound, it shows me the edges of everything, what its made of, if somethings written on it. I've never used my quirk for anything other than seeing things or hearing, without it I can only see blurred colours, no edge, no shape, nothing but colours blurred together. I can see further than anyone else and even places I shouldn't be able to see. If a wall is thin enough that I can hear a sound from the other side, I can see the other side. It's incredibly easy because I can hear everything within a 50km radius, no matter how quiet. But this means that if my eyes can't see it, their just figures without colour. But still, that's how I saw it before he saw it.

I watched or more so listened as the slimy thing raced towards the sewer opening. A man was behind him, I don't know who the guy was but if he was chasing that slime thing, then it was probably bad. The guy was roughly 4 minutes behind the slime guy. I looked at the sewer opening to see a kid. He was clearly trying to muster a fake smile and laugh. I have about two minutes now before the slime guy reaches the grate, the kid will be there at the exact same time. I run forward, about to warn the kid. He's around 14, the same age as me, so I shouldn't be calling him a kid. He's got messy green hair and freckles. 1 minute. I pick up my jog and nearly get to the sewer grate. 30 seconds. He notices me and stops laughing. 15. I won't make it in time. 

"AWAY FROM THE GRATE!" 0. The slime guy leaps up out of the sewer, landing on the boy. He screams and the thing starts wrapping around him. "So you knew I was coming eh?" the slime beast looks at me but starts shoving itself inside the boy. "Leave him alone!" I shout. I don't have anything to throw at the monster, so I dash forwards and jab at what must be its eyes. I'm right though it barely does anything other than make it angry. 3 and a half minutes until the man gets here. The boy starts scratching at the slime, trying to get it out of his mouth. I listen to his breathing. 2 minutes until he passes out, 4 minutes until he's dead, 3 minutes until the man gets here. I have to think fast. The slime thing lashes out at me and I'm forced to roll out of the way. I notice a rusted can and grab it. I thrust it with all my strength at the things eyes. It howls in pain. 1 minute until the boy passes out, 2 minutes until the man gets here. It's illegal to use my quirk to harm him, but this is an emergency, so I'll have to use it so the boy can breathe. I snap my fingers, whilst aiming at the boys face, covered in slime. The force slices through the slime, and I focus on keeping the sound barrier around it. the boy coughs and takes a deep breath before I release the barrier.

"Now your strong, you and your amazing quirk. I think I'll take you instead" his voice sounds like it's coming from someone drinking water and talking underwater at the same time. 30 seconds until the man gets here. Slime guy tries to strike me again, this time from both sides. I leap over him and remove the grate. 5 seconds. I throw the grate at slime guys eyes. He flinches and the man jumps out of the sewer. I recognise him instantly.

"Fear not" he booms, the everlasting grin on his face "For I am here!" he bellows, doing a Detroit smash at the villain. Just the force is enough to tear the villain apart. The boy lays unconscious where the slime dude just was.