Here we go! Part 2! This is where the events of the AU truly begin:
Main Storyline
*Izuku's life follows canon from the original, except that when Katsuki fell off the log when they were kids, Izuku instinctively reached his hand out to him and for a millisecond, Katsuki felt himself go weightless and saw the Absolute Solver symbol appear in Izuku's eye briefly before it fizzled out and Katsuki finished falling into the stream.
*None of the other kids noticed the shift however, including Izuku, but Katsuki knows what he felt and saw. However, in that brief millisecond that to him seemed to last a lifetime, he also felt an ominous presence that somehow he could tell was hungry, like he was being hunted and about to be devoured by an apex predator.
*Katsuki held an instinctive fear towards this presence he felt from Izuku, which he hated due to the fact he despised the idea that anything could possibly scare him, but also because he could never understand how weak, crybaby, quirkless Deku, who was basically mere prey compared to even all the other extras in his life, could have possibly felt like threat.
*Regardless, Katsuki kept an eye on Izuku throughout the majority of their childhood from a distance while simultaneously bullying him to maintain his ego complex, waiting and watching for the moment that apex predator presence would show itself again.
*Izuku still meets All Might as he usually does, but doesn't learn about his injury or other form.
*Izuku fully unlocks his solver for the very first time during the Sludge Villain Incident, using it to defend himself and pull Katsuki free. Izuku is shocked, but accepts the conclusion that it was a rare mutation… though he secretly wonders if that's actually true. Regardless, he decides to make the best of his newfound power and use it to become the hero he always dreamed to be.
*All Might is still inspired by Izuku's heroic spirit and believes the boy would make a perfect successor, but debates on giving him One For All due to Izuku now having to figure out how to use his own "quirk." Even so, All Might still wants to help Izuku unlock his full potential and become the great hero he has shown the potential to be.
*Since Izuku does not know his secret, Toshinori approaches the boy in his true form… or more like tries to be sneaky, tailing him as he debates how to approach, which only frightens Izuku once he notices this strange man stalking him and Toshinori responds, "Wait, young man! I promise I'm not a pervert! Please don't call the police!"
*Once the misunderstandings are cleared up, the two end up becoming good friends, with Toshinori giving Izuku tips and advice while he learns how to use his solver and trains for UA; both Izuku and Toshinori find their time spent training together to be the highlights of their days throughout the next year. Izuku has never been happier than he has with this old man guiding and supporting him in a way he's never had before, while Toshinori for the first time in a long time gets to be a mentor and friend to Izuku as himself, Toshinori Yagi, instead of All Might, the living legend that never falters.
*In the meantime, All Might decides to entrust One For All to Nighteye for him to hold onto until an appropriate time should arise. All Might can't afford to keep holding onto the quirk with his time still running out while he thinks about whether or not he wants Izuku to eventually inherit the quirk after all.
*Nighteye is not happy with All Might's decision of course, and he of all people does not feel worthy to hold onto such a sacred gift, hence why he vows never to use the quirk he has been gifted himself.(The thought to just pass the quirk to Mirio since he now can crosses his mind of course, but out of begrudging respect of All Might, he refrains from doing so till the man says otherwise.)
*Katsuki meanwhile, was left shaken from his near death experience, but it also sparked the beginning of a change within him: the incident made him aware of his own mortality and how easily it could be snuffed out; the trauma of the incident impacted him more intensely than he let anyone and even himself realize.(This was the moment after all, when he stopped smiling arrogantly in class, replaced with more serious and focused scowling.)
*Additionally, while he both immediately recognized and was wary of Izuku's solver the moment it awakened, he didn't fail to recognize not only that Izuku did save his life, but that he used that power Katsuki knew contained a predatory presence within to do so.
*As a result, Katsuki begins to acknowledge and see Izuku and his solver as two separate entities: whatever is in Deku is clearly dangerous, but Deku himself does not pose that danger.
*This also leads to Katsuki beginning to see a separation between people and the might of their quirks, thus he begins coming to an understanding that quirks don't actually affect the value of a person, leading to him resolving himself to become even stronger to guarantee his place in UA, as he now knows his quirk alone won't be enough.
*Katsuki leaves Izuku alone the rest of the school year as his silent repayment to the nerd for saving his life, but he still remains cautious and suspicious of Izuku's newly awakened "quirk," especially now that Izuku can actively use it.
*Katsuki resolves to get to the bottom of the fishiness and threatening presence of the nerd's "quirk" once and for all, and ends up stalking Izuku on his way to training one day, only to see Toshinori with him and think, "Who is that old slender-man and what does he want with Deku? Is he a pervert?"
*On the cautious side, Katsuki ends up spying on the two of them training the entire year, but never says anything, deciding to just watch from afar and keep a close eye on the two, observing all he can of Izuku's solver while simultaneously growing a begrudging respect for Izuku's determination and effort.
*Through analysis, experimentation, and Toshinori's support, Izuku obtains a firm grasp on his solver by the time the UA entrance exam rolls around and becomes quite proficient with it, however he does notice that ever since it "manifested" he's had a much larger appetite than usual.
*He of course changes his diet to accommodate, but can't help but take notice how his blood sugar now seems to drop easily if he doesn't eat enough, and when it does, rather than feeling weak or lethargic, he begins feeling some strange "impulses" to hunt for food.
My sister and I were debating what to do about OFA in this AU, whether we wanted Izuku to still have it, or have it go to someone else while Izuku still maintains a relationship with All Might. Ultimately, we decided to go with giving it to someone else, but with a twist: rather than finding an alternate successor, and another child no less, we thought: what if OFA went to a grown-up this time? And as I tried deciding between either Aizawa or Nighteye, I decided to go with Nighteye as he still is the only one Toshinori would trust with his quirk despite their current strained relationship. Since Toshinori thinks AFO is dead, he's not in a particular rush to find a successor, but he does need to pass the quirk on due to his decreasing time limit, hence why when he finds himself considering Izuku, he decides the best course of action is to help this promising candidate figure out his "newly manifested quirk" first before dumping another extremely powerful one on him, and have someone else whom he trusts be a placeholder until the appropriate time.
Next chapter will cover both Starting UA and the USJ Incident since the changes for this AU are not too long for those respective arcs.