Do_I_Exist_14
Eri was never born, at first, this doesn't change a whole lot. Izuku still becomes the next heir of One For All, Kai Chisaki still becomes Overhaul, maybe having to kill a few extra people here and there.
Until the raid on the Shie Hassaikai, where Eri is not present to help our hero win the fight. After Izuku is defeated, someone crashes into the fight as well, forcing Kai to use his trump card and add our hero's mass to his own, taking his quirk and giving himself an extra pair of arms.
Wait... isn't it impossible for One For All to be forcefully taken?
Izuku is alive after the fight and Kai has disappeared. Maybe the 'personality changes' he's been experiencing aren't due to trauma after all...
(Cross-Posted On Ao3)