The Hero he needed(Male Reader X Fem Deku)

His power

No one pov
It has been 15 years since the birth of Shigaraki's child. His named him Y/n with the insistence from the man Y/n came to known as his "grandfather", who to the world was known as All for one,to take the surname of Shimura to allow zero connection for the heroes to make. Y/n never understood the significance of the his last name but it would come to be learnt later.

All for one also made Shigaraki have some bonding time with his time, which meant he made him prioritize time with him in order to form a " bond" with him. Allowing for the crime boss to make Y/n his puppet. Y/n's quirk was also shown to be more powerful then decay Itself, which made All for one kinda regret not keeping Rose alive along enough for him to steal the quirk that combined with his protege's decay to create this horrifically powerful quirk. The quirk Corruption allowed Y/n is do anything Decay could but he could also use it on gas and liquid state matter. They learnt this when Y/n picked up a glass of water and unable to control his quirk at this he decayed the glass but more shockingly the water turned murky before forming into a sludge that then dried up and turned into dust. And the time they learnt that his quirk could decay gas was the near almost death of Kurogiri. When the gaseous butler was tasked with warping the son and father pair to the good doctor Y/n mindlessly touched part of the gas which solidified into a concrete like matter before cracking. It would have spread if Shigaraki wasn't as quick as he was to get out his knife and slice the decaying part of the gas off. The good doctor deduced that Rose's quirk was possible a fairly useless solidifying quirk that didn't have a base to solidify for the quirk to be useful so mixed with the decay quirk factor that breaks apart solid matter and you get a quirk capable of destroying anything by first solidifying it and then decaying it.

Currently Shigaraki is training with Y/n. The young man has become taller then his father by a few inches and adopted his mother's white hair and his father's red eyes.

They were doing hand to hand combat and Shigaraki was dominating his son. However, Y/n quickly overcame his father and punched his father in the stomach before throwing him over his shoulder to deliver him a fast lost.

All for one Pov
Y/n defeated his father in a battle and from there I knew he was the child of destruction that I wanted to help us wreck havoc on the world. However, as a child he still holds the childish ideology of heroes being sacred beings to himself and values All might as his favorite hero. It makes me sick to my stomach to see him view my rival as being superior to me but one day he will learn who is dominant. Now I called Y/n over.
Y/n:Yes grandfather.
I almost burst out into laughter at his ignorance to my true identity but it revealed itself as only a smile as what I had him do now actually fit.
Me:Your father and I think you are ready to pursue your dreams. So we are giving you permission to enter the Ua entrance exam.
I saw his eyes light up with excitement as he ran out to prepare.
Me:Tomura.
Tomura:Yes master.
Me:Monitor the boy's progress.
Tomura:You mean with 'him'
Me:Yes. Have him watch the boy. After all, the strings that I have pulled allow them within the same place at the time.
Tomura:Of course master.

Time skip
Y/n Pov
I now stood in front of Ua high, the place where my legacy will begin. I began to take my first steps when I saw somebody begins to fall. I lunged towards them with his hands towards as they grabbed the person but I felt something soft as I grabbed them.
Me:Are you ok?
???:Y-yes I am fine but could you let me go now.
I helped them up as I saw the most beautiful girl in front of me who had emerald green hair and eyes and the most elegant fave I ever saw.

She had a giant blush like me across her face and she had her arms crossed her chest. It took me a minute to figure it out as my eyes widened.
Me:I am so sorry I didn't mean to- I mean, I that wasn't my intention but-
I ended up mumbling about more things when she cut me off.
???:It's fine, you didn't mean to. Thanks for helping me up.
Me:Let me start over, my name is Y/n Shimura. What about yourself?
Izumi:Izumi Midoriya. So are you enrolled for the hero course, support course or general studies?
Me:My quirk is only useful for one of them. The hero course. I want to prove those who said my power was onto useful for harm.
Izumi:That is very admirable of you.
Me:Thanks, what about you? Why are you here?
Izumi:I guess you could say we are here for the same reason. To prove people wrong, people who thought I was weak and helpless. Wait you said your quirk was only harmful. What is it?
I took a deep breathe before speaking.
Me:My quirk is called corruption. It allows my to destroy what I touch.
Izumi:But you touched me and I am still standing. Does it not work on humans.
I was surprised what she didn't express extreme fear over my quirk. In fact she conjured up a a notebook and started to write down notes about my quirk.
Me:No it destroys everything my hands touch but certain factors prevent me from causing destruction to everything I touch. The first is my control over it. My father and grandfather trained me so that I can control what is destroyed. But in the instance where I absent mindedly lose focus on not activating my quirk that is where factor 2 comes in. At all times I am wearing 3 fingered gloves. Like my dad, on its own my quirk needs all 5 fingers to activate but covering a large percentage of the fingers stops it from activating.
Izumi:Wow, that is incredible.
Me:What about your quirk?
Izumi:My quirk is-
The rush of students ran past us when we realized we still had to enter the school for the entrance exam. We both bolted into the school and signed in. The students were sorted into their schools but that was a problem.
Me:So I never got any traditional education.
Receptionist:What do you mean?
Me:I never went to school and learnt from my dad but he isn't qualified for home school.
Reception:Ok good enough for me. Go with the girl you were with and take that seat.
I nodded as I sat next to Izumi who was next to some ash blonde kid who reminded me of a Pomeranian.

We start a long exam which I lasted 2 hours. Then present mic begins to explain the exams when a tall blue hair boy stands up.
???:Present mic I was wondering why you missed put the biggest robot. If this is the standard for UA then it is embarrassing. And you!
He points at me as I was listening to music on my headphones my Dad got for Christmas after Present Mic explained the first 3 robots. When Izumi tapped my shoulder I took them off and looked at the all boy with glasses.
Me:What do you want?
Glasses:If you aren't serious about this exam then you can leave.
Me:Well I didn't think I needed to listen anymore considering that the fourth robot you are asking Present mic about is labelled the 0 pointer for a specific reason. Probably because it is worth zero points. Right Present mic?
Present Mic:Uh yeah that is correct.
Me:So maybe you should tighten your glasses or stare at the screen closer because I am pretty sure it is obvious that the zero pointer is worth zero points so why don't you be quiet and sit down.
After that the boy with glasses became silent as he sat down and everyone in the hall began to laugh. After that the students began to line up outside the gates. I was placed in a group with nobody I recognised. The doors opened as Present Mic's booming voice echoed through the halls.
Present Mic:What are you waiting for? Real heroes don't have countdowns.
On that second I felt every bit of what I was learn course through my veins as I blitzed into the mock city and then placed my hands. The ground, buildings, and even the roaming robots turned grey before crumbling into dust. It wasn't even necessary for the other applicant could enter. I felt eyes on me as I left the crowd of students frustratedly yelled at me as I left Ua feeling like a champion.