So had this idea let me know if you want more

BACKGROUND INFORMATION

Izuku and eri are the same age

Izuku's quirk is called fast forward and it's the exact opposite to rewind but it isn't just restricted to organic things however if he uses it too much it can cause internal bleeding which will cause him to vomit blood much like all might only difference that izuku's condition can be fatal if he overdoses it.

Izuku's story

After izuku accidentally fast forward his mother out of existence when he was 4 his father decided to pawn him off to overhaul to pay off a debt where he stayed there for 10 years. When overhaul found out about izuku's quirk is he tore apart izuku and put him back together over and over again until overhaul found eri.

Eri's story

After Eri erased her dad out of existence her mom really did try her best to raise eri but eventually, she cracked, and when she turned 14 eri's mom shipped her off to her grandfather which helped overhaul achieve the last part of his plan.

Pov overhaul

Overhaul's plan was simple, use eri to make a drug that erased quirks and then use izuku to make a cure.

However, izuku seemed uncooperative no matter what he did to the little brat. The only time he seems to obey him was when he threatened to hurt eri and when he actually hurt eri, that was the only way izuku would ever submit to him.

Eri seemed to completely give up she didn't even fight back and he knew that got to izuku.

Something didn't seem right today. izuku put up much more of a fight this time and even managed to fast forward some random who was next to me into dust, after rearranging his molecules around and then back. izuku was silent even more so this time.

Pov izuku

So after distracting them long enough for eri to go get help, I managed to steal a drug I heard about.

It was called trigger and it supposedly made your quirk extremely strong.

The next day

Overhaul brought eri back the next day she seemed fine so I had asked "are you ready"

"Yes. The plan is set in motion the heroes should be coming soon give it a week, they are here" was eri's response.

"And if not we'll just have to save ourselves," I said while holding up two-doses of the drug trigger.

"Um, what happens if the plan fails"

"Then you take the other dose of trigger and run don't worry about me run. learn to master your quirk then come back and save me I'll be here waiting."

"Ok, izuku you promise you won't be mad if I have to leave you here"

"No Eri I won't, I'll be happy because more than anything I want you to live your life so promise me if it does come down to it you'll run, make a life for your self and then come back for me ok, promise me eri promise me please," I said as I began to tear up.

"Ok I promise izuku" she then began to hug me as we slept together.

in the middle of the night I heard "I-izuku can you promise you won't leave me please."

"I promise eri nothings gonna make me leave you And with that I fell asleep.

Pov narrator

The next week went by fast for the duo as they began to mentally prepare for the biggest escape plan they have ever tried.

Now it was time to enact the master plan. Izuku stuck himself with the drug only to be blown back by the power he felt. while normally his quirk was pretty strong on its own he could now fast forward things without having to touch them but only in a certain range. Range Still yet to be determined.

Quickly he began blitzing base as he proceeded to fast forward everything from the people who served under the overhaul to the building its self which resulted in a massive crater. But overhaul was not here as he had left to attend the matter with other yakuza outside of The Shie Hassaikai's control.

"You brat!" he heard overhaul scream as he used his quirk to make spikes to send towards izuku. The problem was izuku could just fast forward the materials into dust before they even hit him. And so a battle began of who could outlast the other.

For 2 whole hours overhaul just kept sending spikes at izuku with him turning them into dust. Until overhaul saw eri trying to sneak past them and run. He decided he could just use eri against izuku like always.

except he didn't expect izuku to go that far for eri. all he saw was izuku use his quirk on himself then a brief green flash then darkness was all he saw.

Pov night eye

After getting a very helpful tip from some 14-year-old girl they were able to storm The Shie Hassaikai base of operations. The only problem is that there was a massive crater that looked like something with 3 basement floors that had caved in on its self and everything looked like it was over 100 years old which is weird considering everything in this area is less than 50 years old.

I hear Eraserhead shout that there were kids at the bottom of the hole in the ground quickly Eraserhead rock lock and fatgum and I all rushed down there and the sight we saw was oddly disturbing.

Pov Eraserhead

When we arrived down there we saw two kids both quirks were active one had green electricity flowing out of him and the other one had a golden aura she seemed like she was struggling to keep control of her quirk.

"Izuku it's ok I'm here you don't worry you'll be fine," the girl said.

Then the boy. izuku said something that made the hair on the back of the neck stands up. "It hurts eri please just stop"

"No izuku you promised me you promise you wouldn't leave me please izuku!" I heard the girl scream quickly using my quirk I stopped both of their quirks which seemed like a bad idea.

As soon as eri passed out izuku began vomiting up blood and large amounts of it. It remained him about someone he just couldn't think of it now in this stressful situation Before he too eventually passed out.

Quickly rushing both of them to the hospital all we had to do is wait mainly because they were the only witnesses to what happened.

So new story um let me know what you think.

Sorry about the mistake I made I'm just an amateur. Next time we'll see them in the hospital.