Well, one possible plotline could be Izuku's struggle to control the sudden influx of power from One For All at an earlier stage than in the original story. He might face challenges in keeping it a secret from his classmates and teachers, adding a layer of secrecy and tension.
Obviously, Izuku Midoriya is the main character as he is the one mastering One For All early. Katsuki Bakugo might also be prominently involved. Since he has a long - standing rivalry with Izuku, his reaction to Izuku getting such a powerful quirk early on could be a major part of the story. Maybe he feels jealous or challenged in a new way.
Izuku's character would likely be very different. He might be more cynical at first. Since he's raised by All for One, he would be exposed to a lot of villainous thinking. But as he grows, his inborn sense of justice could start to resurface and cause internal conflict.
You can try websites like Archive of Our Own (AO3). It has a large collection of fanfiction for various fandoms, including My Hero Academia where Izuku and these powers are from. Just use the search function and type in relevant keywords like 'Izuku' 'All for One' 'One for All' to find the fanfictions you're interested in.
One interesting fanfiction could be where Izuku uses the combination of All for One and One for All in unique ways to defeat powerful villains. He might use All for One to take away the quirks of enemies and then use One for All to enhance his physical abilities to an even greater extent than normal.
The 'Return to One' might be referring to the ending of the novel,'The All-time Master'.
" Full Time Expert " was an esports novel created by Butterfly Blue and was published on Qidian Chinese Network. On July 12, 2017, Qidian Chinese Network obtained the serial authorization and ended in 2019.
The novel told of Ye Xiu, a top-class expert in Glory who was hailed as a textbook. Due to various reasons, he was expelled from the club. After leaving the pro scene, he settled down in an Internet cafe and became a small network manager. However, with ten years of gaming experience, he re-entered the game in Glory's newly opened tenth server. With his memories of the past and an incomplete self-made weapon, he began his journey back to the peak.
" Full-time Expert " won the top ten best works in the ten years of online literature inventory activity, and won the honor of " Hundred League Glory " celebration on Qidian Chinese Network. In May 2018," Full Time Expert " was ranked second on the " Hurun Original Literature IP Value List."
While waiting for the anime, you can also click on the link below to read the classic original work of " Full-time Expert "!
One possible plot could be that Izuku, under All for One's influence, has a completely different view of hero society. He might be trained in unique and perhaps unethical ways, leading to a conflict within himself as he tries to figure out his own identity and what it means to be a 'hero' or a 'villain'.
The League of Villains would be obvious antagonists. They'd see Izuku with the All for One quirk as a threat or a potential recruit. Shigaraki, in particular, might be envious and want to take the quirk for himself.
There could be some original characters created by the fanfiction writer. For example, a mysterious mentor figure who has been secretly training Izuku in a special technique that he can use against All for One. This mentor could have their own backstory and motives that are intertwined with the main plot of the fight.
Well, in the fanfic world of 'All for One Izuku', his character development is really interesting. At the beginning, he's this innocent kid who suddenly has this huge, dark power. He struggles a lot with whether he should use it or not. As time goes on, he realizes that the power itself isn't inherently good or bad, it's how he uses it. So he starts to train hard to master it. He also becomes more street - smart and less naive. He has to learn to deal with the villains who are after his power, and this toughens him up. He starts to see the grey areas in the hero - villain dynamic and uses his power to create a new kind of heroism that combines elements of both sides.