A Quirk Through Time/Villain Swap AU

Prologue

It was a normal evening like any other as All Might would jog around campus, but when trodding on the path through the forest he came across a girl in the center of the path.  Her blue piercing eyes were staring at him as her white hair lightly fluttered in the evening breeze. Her face was stoic as if all emotion has been drained from her pale white skin.

"Ah Young one what are you doing out late it's past curfew," All Might states.

The girl was wearing the standard UA uniform and a black coat with the hood partly over her face. 

"You have been calling for me," She says.

"Calling for you? I don't mean to be rude young one but I'm not sure who you are," All Might says. 

"My name is Era and your wish has been calling for me. My quirk allows people to travel in time," Era states.

"Travel back in time? Isn't that dangerous?" 

"Yes All Might, but you were the number one hero and my hero. I am willing to grant you your wish. There is more, you will be paying a price for travelling back in time. My quirk can only transfer those who have the ability to pay the equivalent price," 

"What do you mean equivalent price?" 

"Money, World domination, things like that I cannot grant. Most people cannot pay the equivalent price for the ability to travel back in time."

"If you're approaching me then you think I can pay the price?" 

"All my quirk allows me to know is that you can pay, what you lose I do not know." 

"I'm sorry Young Era but even if I did take you up on this offer I don't know if I can save him like this."

"You will be going back in time to the body you inhabited at that time. The memories you have however will only be what you knew at that time, and the memories retaining to the wish."

"I'm afraid to ask but how do you know so much about your own quirk?" 

For the first time since the conversation began she hasn't shown any emotion but this question made her eyes deviate from All Might's. 

"A quirk that affects time cannot be affected by time, but since I am not affected I can barely interact with it. I do not want to talk more about it." 

All Might listened to Era, his heart clenching a bit as the girl probably suffered a lot due to the effects of time travel. To know so much about a quirk she must have used it enough that this probably isn't even her proper time.

"I have one more question if you don't mind, how drastic are the changes?"

"Your day-to-day life will change but there won't be major changes from then to now, you will still retire after beating the villain in the Kamino incident."

"All right, I will do it."

Her piercing blue eyes begin to glow brightly as space around All Might slowly compact before disappearing into nothingness.

"I truly hope the future that awaits you is what you desire."

Meanwhile, in the not-so-distant past, a young boy with green hair cries while on his knees with his mother lying dead on the floor. A Hero overusing their quirk accidentally destroyed half the apartment complex with the boy's mother trying to shield his body from the blast. His father had died before he was born but never knew the details and now his mother was killed.

 This was wrong, everything felt so wrong to him. Where was All Might? Where was the person who always saved people with a smile? 

"All Might!" the boy cried as loud as he could.

"The Heroes couldn't save you huh.." A voice said coming from behind.

Slowly turning around the boy looked at a man who was wearing a suit, the top half of his face was destroyed but the boy knew that the man could still somehow see.

"It must hurt, Izuku Midoriya." 

"H-How do you know my name?"

"I am All For One, I know many things. I also know why this happened to you."

"P-Please tell me why, why did this happen to my mother!"

"Of course, but this isn't a good place for a conversation," All For One stretches his hand out.

"I-I don't know if I should Mr. All For One"

"I understand, but if I told you that this was never supposed to happen and it only happened because All Might traded your life for another, would you be more willing to hear me out?"

Izuku shakingly took the man's hand.

"Please tell me more."