Yandere! BNHA x reader Oneshots

My Eri (Overhaul x Gn! Reader) pt. 1

Boy oh boy! It's time for another chapter!

And what is dis???

It's angst!!!!

Yeah... this is gonna be kinda f***ed up.

Basically, Mc becomes a lab experiment for Overhaul and grows kinda obsessed over Eri (IN A PLATONIC, MOTHERLY WAY, NO PEDOPHILIA IN THIS HOUSE, FOLKS)

Overhaul is a soft yandere in this but still does fucked up stuff like an Overhaul does.

⚠️Warning⚠️ Death up ahead.

And yes, the art up there is you

~~~~~~~~~~~~~~

Kai had to keep it together when he looked through the glass to stare at the mutated being.

You were no longer your sweet, gentle self but instead a monster. A lab experiment gone wrong.

He didn't want to do this, in fact, he was perfectly fine with you not agreeing to be a test dummy... but you did. You whole heartedly volunteered to become a test subject.

You were is closest friend for the longest time, before he became so bitter and cold. Before he took Eri.

He didn't want you to find out what he had been doing, what he had done to that poor girl... but you did anyway.

Your reaction wasn't what he expected if he was completely honest. You didn't hold anger nor hatred, but instead sadness, betrayal, and disappointment.

You looked at him as if you had lost a friend, and he hated it. He wished you hated him. That you called him a monster...

But instead, you chose to sacrifice yourself to ease the little girl's pain.

It took him minutes to compose himself when he stuck needles into your body, knowing that whatever he injected you with could potentially kill you.

He did many kinds of tests, even trying to transfer Eri's quirk to your body (you insisted on it), but none worked.

What happened instead was your body twisting and contorting into something else.

He didn't understand, he couldn't comprehend why it happened but believed it had something to do with Eri's quirk that lingered inside of you, shifting and contorting you.

You had a grown a horn similar to the little girl, only longer and sharper. In fact, you grew horns everywhere on your body, jagged and long.

"...Eri..."

It terrified him beyond belief, seeing his lifelong friend get infected so terribly by this... illness.

Despite his promise to make Eri's life more easy, he took out his anger and stress on the girl, never letting up on his torturous methods. He blamed what happened to you on Eri and would continue to torture her until the day the heroes broke into his facility.

"...Eri..."

He walked through the facility with Eri in Chrono's arms before that blonde kid, Lemillion, showed up.

"...where is..."

While the two of them spoke, somewhere else inside the facility was you. You weren't focusing on the people at your door, peering through the one way window but instead on Eri. You could feel her distress, her fear.

"...My Eri...?"

That same day, the man who called himself Overhaul spoke to you, talking to you as if you were an old friend of his. He looked at you with such fond eyes, only hardening when you spoke of Eri, which was all the time. You asked him over and over and over again where the little girl was, but he wouldn't listen.

You could smell your little Eri's blood on him.

The large metal door slid open quickly, revealing men in uniforms. They seemed to pause at your form, seemingly frightened by your appearance.

"...it's okay... we're here to help you." A man with a black mask and a torn bright yellow jacket said gently.

"FatGum, I'm not sure-"

You suddenly bolted towards the men, shoving and charging them. They weren't your targets, so you left them with scratches and bruises.

No.

You were after one thing.

And that was Eri.

Your long limbs helped you to tear through the hallways, speeding past the police and yakuza, who were tied down.

The first thing you were met with was light. This area, this 'room' had the largest ceiling made of blue... no wait, that's not the ceiling... and this isn't a room.

"Hey! Stop right there!"

"What the hell is that!?"

But you weren't focused on the voices, but instead the young girl in an unfamiliar man's arms.

Eri.

That was your baby Eri.

You didn't hesitate to rush towards the two, scaring the man holding the feverish looking girl in his arms. A kid in green jumped in front of him, glaring you down before a his narrowed eyes widened.

You pulled back your clawed hand and slapped him away. While you backhanded him, something slipped around your neck before tightening and pinned you to the ground.

"Hold your fire! Get the child out of here!"

You growled and hissed, snapping at the men surrounding you before noticing the man holding Eri rushing away. Your angry roars turned to cries of anguish, shrieking the name of the girl you longed to protect.

The teen you nearly knocked out stood up shakily while holding his bruised cheek. He watched as you were dragged away in chains like an animal, away from the girl you sought after.

Midoriya wasn't the only one who could hear your pitiful cries, though.

Although Overhaul was barely hanging on to consciousness, he could recognize the mournful sounds as yours.

"...(Y/n), I'm..."

His eyelids were slowly closing but he still held on.

"...so sorry... Angel..."

~~~~~~~~~~

Let me explain Mc's new quirk.

Mc was supposed to inherit Eri's quirk so she didn't have to be torn apart to make quirk destroying weapons. unfortunately, it went wrong and instead of have the ability to rewind, it mutated Mc into growing horns similar to Eri's little horn all the while making Mc more aggressive and animalistic.

This is due to Eri's quirk accidentally messing with Mc's evolution, mostly mentally.

Why didn't Mc report nor try to stop Overhaul from experimenting on Eri? He wouldn't have let them get to the police after Mc discovered his secret. Mc knew they wouldn't be able to convince Overhaul no matter what Mc did, so they wanted to take Eri's quirk so they could suffer instead of Eri.

Why did Mc become obsessed with Eri?
During Mc's tests, they had interacted with her a few times and had always thought about Eri since they were doing all of this for her. Unfortunately, due to the mutations claiming not just their body, but their mind, The need to protect Eri grew tenfold to some unhealthy degrees.

I'm planning on making a part two where U.A tries to help Mc and Eri recover from not just their physical scars, but emotional scars. When they notice Mc's attachment is incredibly unhealthy, they try to help them as best as they can without causing them to go on a rampage.