All of the AUs I have been reading lately have Todoroki as a hero student thats lead to villainy by a villain deku but what if it was the other way around.
Shoto gets contacted by his brother (Dabi) at some point and joins the villains to get away from his father. Also lets be honest with that kind of upbringing theres no way his senses of morality or love are normal.
So Shoto sticks around to be the UA traitor and starts scouting Midoriya.
The sports festival is flip flopped with Midoriya challenging Shoto to use his fire when in canon Shoto declares war. Midoriya tells about his experiences being quirkless and all of the bullying instead of Shoto telling his life story. This trails into a rant about Shoto using the powers hes born with and being grateful for them. (Bakugo still ease drops but instead of hearing about Shoto learns exactly how close izuku was to jumping off of a roof at one point)
Shoto uses this to coax Midoriya to his side making him doubt if he would have anyone around if he still didn't have a quirk. This leads to some shocking comments from some classmates that make Midoriya rethink his views of his classmates and what impacts he could make as a villain. Hed be the perfect person to argue that heros aren't always as they should be with his father as a prime example while introducing him to the stories of some of the villains and how some things just cant be fixed legally.
Sprinkle in some fluff and personality changes for Shoto and I think that could be a great start.
I think it'd be cool to involve some traitor eraserhead as well, like he over hears the quirkless comments and Shoto convincing Midoriya and is slightly convinced himself but takes it slightly more independent or has just been doing it for a while already. (None of his students with abusive families end up having the parents survive through second year as a mysterious villain kills them at some point)
