My Hero Academia one-shot idea
Four groups of several people appear. Izuku is one of them, and just like most of the others he's rather confused. The weirdest part is that there are some multiples of the same person. There are three Bakugos, four skinny All Mights, three Sir Nighteyes…
One group in particular calls for attention to explain. A Mirio is there, looking particularly worn and shaky. Their groups’ All Might and Sir Nighteye explain that they were in need of advice, and they requested the help of someone with a unique quirk to summon three other groups from alternate, but close-by, timelines to chat for an hour. Everyone present is connected to their dimensions’ version of One-for-All and the one that wields it.
The advice they need is in regards to possible wielders of One-for-All. Their Mirio holds it for them, but he’s had an averse and damaging reaction to it.
There is at least one Tsukauchis present, and he confirms the truth of their words.
Another group, other than Izuku’s, pipes up with the knowledge that One-for-All cannot safely be used by anyone who already holds a quirk. For that group, their OFA is currently held by Melissa Shield, but she admits that she’s not a hero, and just acting as a holdover, after taking it from Kirishima. They’re looking for a new wielder too.
Izuku realizes he’s the only version of himself present. His own group is glancing at him with wide eyes. His own All Might has a hand on his shoulder.
The last group of the three summoned doesn’t include anyone his age, nor anyone quirkless. That group’s All Might admits he hasn’t chosen anyone yet to attempt to give the quirk to. He’ll keep in mind the condition that they must be quirkless. One-for-All may just die with him.
Eyes fall on Izuku’s group, and Izuku steps forward with All Might by his side. There is no Sir Nighteye to accompany his group.
Before he has the chance to introduce himself, the two Bakugo, belonging to OFA!Mirio and OFA!Melissa, shout out “DEKU” in shock, and Izuku’s Bakugo shouts at them back. OFA!Mirio’s Bakugo looks angry, but OFA!Melissa’s Bakugo looks stunned. Izuku watches him, as he alternates between angry and sad and… something else.
Through the shouting, it’s made clear that OFA!Melissa’s Izuku is dead. That Bakugo mutters out that it was a month after the Sludge Villain. Izuku thinks he has an idea of how he died, and why Bakugo is reluctant to share. The other Bakugo, and Izuku’s own, look baffled. The group of adults with the All Might that still has OFA, look confused by the reference to the Sludge Villain.
Izuku speaks up, finally properly introducing himself, and explaining quickly that he met All Might briefly just before Kacchan got captured by the Sludge Villain, and had proved himself to All Might during that encounter. All Might explained that Izuku was, in fact, quirkless before receiving OFA, and they were totally oblivious to the bullet they apparently dodged.
OFA!Melissa’s Bakugo looks stricken. He stares at Izuku, but Izuku can’t quite meet his gaze.
OFA!Mirio’s Bakugo was being questioned quickly by his All Might, but he hadn’t been in contact with Deku since middle school, he didn’t know what the nerd was up to. It’s not like he knew the quirkless requirement for OFA until now.
In the meantime, OFA!Mirio and his Nighteye approached Izuku’s group to ask more pointed questions about Izuku’s time with OFA, and Izuku’s character. They seemed at least a bit relieved that one of the three groups had a viable wielder. Izuku hopes that version of him is still alive, and didn’t give in to Bakugo’s taunts—he’d certainly get the turnaround of his life.
(I only specified a few people, but I imagined several people for each group, and they could include Nedzu, Recovery Girl, Tsukauchi, Gran Torino, maybe even David Shield for OFA!Melissa, or others that don’t know in Izuku’s timeline)
+ the groups extend to those who aren’t necessarily in the know, like Aizawa, or some of Izuku’s classmates, and they want an explanation
+ OFA!Melissa’s Bakugo confronts Izuku
+ OFA!Melissa’s Izuku’s suicide is revealed, and Izuku’s group get Concerned
+ OFA!Mirio’s Izuku turns out to be alive, and is approached afterwards and revealed to be a vigilante
+ OFA!Mirio’s group has interacted with Izuku’s vigilante persona before
