A/N: We're playing fast and loose with the canons of both Miraculous Ladybug and Boku No Hero Academia.
"Tikki…"
"This was a tragic battle, my bug." A little red creature stated somberly.
"War often is, Sugarcube," Another creature of the same size only in black circled the creature identified as both Tikki and Sugarcube "There are no winners in a war, only losers, the ones who lost more and the ones who lost less."
"Isn't that a bit harsh, Plagg?"
"But you can't deny the truth in the statement, can you?" Plagg circled the red creature. "Question now is, what will your bug do now after all this?"
Both Tikki and Plagg looked at the teen before the two of them.
"We lost so much in this war," The girl stated. "As much as I want to restore the world before All For One's escape from Tartarus by using the cure, I don't want Deku's victory to have been so meaningless in doing so."
"If only that vindictive woman didn't get ahold of Nooro, this wouldn't have happened," Plagg spat out. "She made freaking Hawkmoth look moral despite everything he did."
"I know there's the wish…"
"No- !"
"I'm not going to make a wish," The girl shook her head. "Everything would just be the same in the long run."
"Did you get the Akuma that gave All For One his ability to store quirks and not let it mutate him into a monstrosity without his say-so?" Plagg questioned.
"No," The girl shook her head as she watched people rush the severely wounded to the hospital, which was everyone. "The Akuma had been forcibly fused with All For One's physiology, giving him permanent access to his ability."
The girl glanced around and saw people loading the injured into several helicopters that had landed nearby.
"Say, would I be able to resurrect the people who were killed months ago because of this war?"
"I'm sorry, my bug, but too much time has passed to even try, even if you used your Lucky Charm that day and again now..." Tikki trailed off
"I see."
"But what if their souls can?"
An unfamiliar voice inserted themselves into the conversation.
The girl quickly went on alert, leaping forward before turning to face the person who interrupted her conversation.
Standing before the girl was a man with an ethereal glow, though he appeared very translucent. He wore a simple shirt and pants.
"Who are you?" The girl asked, ready to call the Kwamis to her side.
"You may call me, One for All." The man, One for All, introduced himself with a slight smirk.
"Like Deku's quirk?"
"Like Deku's quirk." The ethereal man nodded.
"If I may ask, how are we seeing you?"
"You look like as if you're a ghost."
"That's because I am," The man nodded. "I've known that other sources of power, aside from quirks, have existed since before the era of quirks, but alas, my brother made sure that those other sources would not challenge him and his rule."
"You're AFO's brother, aren't you?"
"Yes."
"Wait, let's go back, what do you mean the souls could?"
"The souls that have died in the recent war and the war a few months back can still be called back for one last time, but they can only appear in the vestige world and communicate their goodbyes to everyone they ever cherished," One For All stated. "Resurrecting people, even the ones that died today, would upset the balance of the world far too much."
"That is true." Plagg nodded.
"No, the people who died today can still be brought back." Tikki denied. "Unlike the previous wars, it hasn't been a day since they all perished."
"That is why I'm here." OFA shook his head.
"You were never planning on letting the people who died now to be resurrected, don't you?" Plagg accused the ethereal man.
"No." OFA accepted the accusation. "I have an even more selfish plea."
"Selfish?" The girl couldn't help but question.
"With the Miraculous Cure, I was hoping to guide it to heal the most severe of injuries the currently living have acquired."
"Hoping to guide it? How?"
"I am One for All."
"You're… You're actually Deku's quirk!" The girl exclaimed. "You weren't simply naming yourself after his quirk!"
"Yes, while I named myself after Deku's quirk, I was its first user and my will and the wills of the other users can guide the miraculous ladybugs into healing rather than opening old wounds."
"What do you say, Sugarcube?"
"Miraculous LadyBirds!"
A loveliness of Ladybugs, or Ladybirds as they were identified, appeared as soon as the girl, now in red spandex, threw the black-spotted red toothbrush in the air as seven differently colored embers surrounded the magical ladybugs and began to repair the damage the war had done everywhere as well as putting every living combatant out of critical condition.
We see the doctors preparing to examine the unconscious blonde's arm when, in an instant, his arms and body are healed to some extent. The previously damaged hand, though still scarred, no longer shows the severe damage it once had.
Beside the blond appeared Edgeshot, in full glory, confused as to why he was suddenly outside the blond's body.
In another room, two unconscious patients were surrounded by a swarm of ladybugs, momentarily glowing in the colors of the rainbow before the light faded, unnoticed by anyone.
The loveliness of ladybugs soon disappeared as soon as it restored all the destroyed areas because of the war, because of the escape detained villains, back to their former glory.
"That should do it," One For All reappeared behind the ladybug hero. "And thank you for granting us this one request."
"Anything for the world."
Rest well, Ninth," whispered a long-haired, caped woman to the sleeping form of a green-haired boy. "You will burn through the last of your embers before you can meet us again in this world."
"Not unless he'd be affected by a quirk that forces his cooperation without his consent," Another person considerably younger than the woman, commented.
"It'd be nice if he were to gain access to us again as soon as possible."
"Not to worry, unlike the eighth, we managed to leave him a considerable size of the quirk's flames, not unless he has to fight another All For One, it'd be a very long time before he'd use up everything." The person who identified himself as One For All appeared between the two.
"And Unlike All Might, he won't have a time limit to be a hero." The caped woman nodded.
Several months have passed since the war against All For One ended. People have begun to move forward, recovering from the losses they suffered during the conflict.
In the months that followed, people began reporting dreams of those they had lost. In these dreams, their loved ones either said their goodbyes or offered reassuring words.
All of Class 1A dreamed of their fallen teacher, Midnight, and shared how proud she was of everything they had accomplished. Whether it was putting Gigantomachia back to sleep during the mission where she lost her life, or managing to bring Machia to All For One to create a distraction, she expressed her pride in them.
Eraserhead and Present Mic both dreamed of the fallen trio from their group, in addition to dreaming of Midnight. In their dreams, Oboro expressed how proud he was of his friends for giving him the chance to be a hero, despite the brainwashing he had fallen victim to.
Toshinori mentioned that he dreamed of Sir Nighteye and how relieved he was that the future he had seen through his quirk never came to pass.
That he was still alive to this day.
Izuku also dreamt of Sir Nighteye, but all he gave him was a nod of approval.
Izuku also dreamed of the past holders of One For All. They didn't speak or move, but they were there, smiling at him.
Even the girl who had used the Ladybug Miraculous to cast the Miraculous Cure that day dreamed of the people she lost in the war. In her dream, they all shared a final, tearful goodbye.