u/Frosty_Cry7213

Izuku: "One blow to the head!"

(Izuku lands the blow before kicking Overhaul into the wall)

Overhaul: "how am I losing? Am I that weak? How am I supposed to bring the yakuza back to the top of society if I can't even beat a teenage brat like him? I'm sorry boss, I was too weak.

(Bubble girl and Centipeder get into the room where the battle is taking place)

Nighteye: "How? Me and him were supposed to die here, but he beat Chisaki, maybe I was misremebering things (activates foresight)

Mirio: "Get Eri out of here! It's not safe for her!"

Nighteye: "Wait! Bubble girl, Centipeder, get away from her! She's dangerous!"

(Eri grabs both Bubble girl and Centipeder and rewinds them out of existence, before running towards Overhaul)

Izuku: "Eri, what are you doing?"

(Eri briefly touches Izuku and rewinds him back to his injured state after he fought muscular)

Overhaul: "I apologize for my incompetence, boss"

(Eri rewinds his injuries)

Eri: "You can apologize after we escape from these cretins"

(Nighteye grabs Izuku before he can be impaled by Overhaul's spikes)

Izuku: "what's going on, why is Eri helping Chisaki"

Nighteye: "it's because the Eri you saw was a facade, she's not the helpless girl you and Mirio thought she was, she's the true head of the Shie Hassaikai"

TLDR: Eri is the true leader of the Shie Hassaikai and Overhaul is her right hand man who was pretending to be the leader.

Continuation of this prompt: https://www.reddit.com/r/BokunoheroFanfiction/s/p0PMUmLBKX

(Izuku, Ochaco, and Tenya are fighting Geten ro try and get to Shigaraki, as Geten attempts to send a cluster of icicles to impale them a wall emerges, blocking the attack)

Izuku: "who-?"

(Izuku spots Overhaul)

Izuku: "CHISAKI!"

(Izuku attempts to attack Overhaul dodges the attack)

Overhaul: "Calm down, I'm on your side"

Izuku: "Why should I believe you?!"

Overhaul: "Because Deku, I'm your older brother"

Izuku, Tenya, Ochaco: "What?"

Overhaul: "Like I told you, Deku, I'm your older brother"

Izuku: "But I'm an only child"

Tenya: "How are you sure Midoriya is related to a rapscallion like you"

Overhaul: "Because I have memories of him as a child, and my memories never lie"

Tenya: "so he isn't just a rapscallion, but a insane one"

Ochaco: "Just because you're helping us doesn't mean we're going to forget about what you did to Eri"

Overhaul: "That was a long time ago"

Ochaco: "It was a month ago!"

Overhaul: "And I didn't know I had a younger brother a month ago"

Repost since the original post was deleted

Deku: One blow to the head!

(Overhaul gets hit in the head)

Overhaul: You pest!

(Overhaul punches Izuku into a wall, which causes the room to collapse, covering the opening in the wall where Mirio and Eri escaped through)

Overhaul: You just had to ruin everything. Everything I've worked towards, everything that I had planned, this will be retribution!

(Overhaul readies to disassemble the unconscious Izuku)

Overhaul: Die!

(Overhaul attempts to land the attack on Izuku, but he stops before he can make contact)

Overhaul: W-what?

(Overhaul starts to recall memories, memories that never happened)

Overhaul: You're m-my...

(Overhaul escapes through an opening he makes in a wall and promptly closes it just as the debris covered door is smashed apart by Fatgum)

Lock rock: Where's Chisaki?

Ochaco: IZUKU!

(She runs towards Izuku as he regains consciousness)

Izuku: Ochaco? Wait, where's Chisaki! I have to-

Lock rock: he's gone, kid. We don't know where he went

(Elsewhere)

(Overhaul hides in an abandoned warehouse a good while away from the compound)

Overhaul: I-I didn't know that. But how is he, my younger brother.

TLDR: Overhaul got hit on the head and now thinks that Izuku is his Younger brother.

A 18 year old Midnight was walking down the street on patrol. As she was rounding a corner, she noticed a child no older than 14 walking by himself, worried about the child she ran up to him

Midnight: Excuse me, little boy, but where are your parents

The child turns to her, his golden eyes meeting her blue

Child: I don't have any.

Midnight: You shouldn't be walking around by yourself. It's dangerous, especially if a villain attacks. How about I take you to the agency I work at, look, I'm a hero

She shows her hero license to the young boy

Child: it's not like I have a choice.

Midnight starts to guide the child to the purple revolution agency

Midnight: Oh right, I almost forgot to ask, but what's your name

Child: Kai, Kai Chisaki

TLDR: Instead of being adopted by Pops, Chisaki is found and later adopted by Midnight

Dr Garaki: Well, you see, Tomura attacked a prisoner transport carrying Kai Chisaki

Afo: So?

Dr Garaki: Chisaki's restraints came loose during the assault and, well, Tomura, Dabi, and Mr Compress were all killed when Chisaki escaped.

Afo: So, who's body am I in then... (he looks in the mirror only to see Toga's face)... Oh no.

TLDR: Shigaraki died, and Toga is now All for one's vessel.