Izuku gets diagnosed as quirkless when he was 4 years old.
Everyone regarded Izuku as an oddity. It wasn't really because of his quirklessness, but because of his unusual personality. He was kind and compassionate to everyone including his bullies. Classmates exploited his good heart in all sorts of ways and took his kindness for granted. Even when bullies broke his bones and left him bleeding, Izuku still treated them with an understanding heart. His own mother scolded him, saying that even though kindness is a good trait, it was simply too much in his case. Initially, Inko loved Izuku dearly for being a good and compassionate boy, but she soon became concerned. At some point, Inko finally snapped at Izuku, yelling at him for being a dumb pushover. She then hugged him and cried. When asked why she was crying, she simply replied that he won't last in the cruel world, that he will most likely die soon due to his quirklessness and exploitable heart. Inko then promised Izuku that as his mother, she will protect him with all her might-
-As if Izuku was fragile glass, already on the verge of cracking.
The situation only worsened when Izuku said that he wants to be a hero so he can help people.
When Izuku turns 13, he starts hearing a voice in his head and as days pass, the voice gets louder and louder. Izuku cried for joy at first, thinking he wasn't quirkless and was only a late-bloomer, thinking that the mysterious voice was his quirk. But now, Izuku weeps every time the voice speaks up, a reminder of the fact that men aren't born equally. Maybe it was because of the voice telling Izuku things. Bad things. Villainous things. The voice wasn't actually conversing with Izuku. It was more like a one-sided relationship where the voice told Izuku bad things and not replying to any of Izuku's words.
Everyone disregarded him for being quirkless, disparaged him for his endless kindness, and even became crueler when they learned Izuku apparently hears a voice in his head. They thought him crazy. Laughed at how unfortunate Izuku was for not only being quirkless and dumb, but to also be crazy. Classmates avoided him as to not get infected by his quirklessness and stupidity.
Izuku finally broke and cried and cried unto the heavens, asking why life was cruel to him even though he did nothing to deserve it. Asked why his peers responded with violence and cruelty to his actions. Wondered why even his own mother disapproved of his behavior. Izuku yelled at God Himself, blaming him for putting a villainous voice in his head.
After several hours of ranting and yelling, Izuku dropped to the ground with panted breaths. He then mutters "I wish i had a better quirk. Even useless ones are better than a villainous voice."
...
"Please...someone tell me i'm not crazy. Someone tell me i'm not stupid. Someone tell me that it's not a bad thing to be kind. Please. PLEASE. PLEASE!"
...
"...please..."
...
"...please...All Might...anyone...someone...save me..."
...
...
...
"Don't worry anymore Izuku! It's okay! Things'll be alright from now on! Why!? BECAUSE I'M FINALLY HERE, BABY!"
It wasn't God or All Might, nor was it a hero or a villain or even a civilian. Of all who could have replied to him, it was the Devil Himself.
Author's notes (ツ)
Inspired by the fictional duo Jekyll and Hyde. Also inspired by the characters Dr Jekyll and Mr Hyde in the 2017 film The Mummy. It's a great movie if you ask me.
Anyway, in case you're wondering, then no. The voice isn't d***pool. Also, please take note that the voice isn't Hyde either.
To those who would want to see an update of this idea, then worry no more. Because I'm already planning to turn this idea of mine into a full-blown story. So stay tuned if you want to read more of Izuku and Deku.