TodoDeku/Midoriya Experiment AU
In this AU, Midoriya is All For One's biological son. Inko dies when Midoriya is two or three, so Midoriya is in AFO's custody. AFO doesn't care much for Midoriya, so he just kind of... leaves Midoriya alone. Midoriya does online schooling, and at some point meets the doctor. He becomes the doctor's little lab assistant, creating new drugs and serums and things. The doctor becomes a father figure for him. But AFO wants to turn Midoriya into a nomu because it doesn't seem like he's doing much of anything useful. After a long few years of arguing with the doctor, around the time of the Kamino Ward thing, AFO decides he doesn't need the doctor anymore and kills him. As a sort of peace offering or something of the sort, Midoriya is "gifted" to Overhaul because AFO doesn't care. Overhaul experiments on Midoriya and uses him as a babysitter for Eri. Midoriya plans an escape for himself and Eri, and they make it away. To protect Eri, he gives her to Aizawa. Aizawa never sees him, but he was given a note explaining the situation. Eri was asked not to tell anyone anything about Midoriya, and told that Midoriya would try and visit her often. Midoriya goes off to take care of things on his own, and becomes a vigilante.
A few other things that I feel would be important to note:
-Midoriya is very insecure about his appearance, he has scars all over and because of the experiments his body has been modified.
-Midoriya is a fairly well-known vigilante, at least to the police force.
-He tries to visit Eri at least three times a month.
-The doctor didn't have much empathy and was still an overall terrible guy, but he was a good and caring father figure, if not the best role model.
-Midoriya is good at hacking, coding, and building, as well as medicine and chemistry and math. He learned a lot of skills during his time with the doctor, so despite never having gone to school, he has a college-level understanding of a lot of things.
-Midoriya has Chronic Pain.
-He knows what the doctor did, and isn't very proud of having helped. He did however try to make it as painless as possible for the people who were being turned into nomu.
-Mineta didn't die at USJ, but he did give up on being a hero afterwards.
-Shinsou was put in the hero course in place of Midoriya.
-Kirishima got One For All.
-Shinsou and Kirishima were the ones saving everybody's asses, so nobody died, although injuries were often more severe than in canon.
-Kirishima doesn't break his bones like Midoriya, he solved the problem pretty quickly, although he won't be able to use OFA to the same extent as Midoriya would have been.
-Endeavor hasn't really changed much. He says he's trying but not much has really changed.
-Besides the doctor, Midoriya has never had anyone to fill a parental roll, and the doctor was an evil maniac who experimented on people and is now dead, and Midoriya hasn't experienced a lot of things that are considered "normal".
-Iida lost his arm during the stain fight, but he now has a robotic arm and Kirishima, Shinsou, Aizawa, and Todoroki (who showed up last minute with Endeavor) saved his ass.
It's nearing the end of the first year when Todoroki meets Midoriya. It's during a break, meaning Todoroki had to go home, so Todoroki snuck out that night to get away from his dad. Midoriya got injured during patrol, and Todoroki hears him in the alleyway muttering a bunch of very creative and colorful curses. Todoroki helps Midoriya, and they bond over their shitty fathers. They start dating around four months into Todoroki's second year. Eri was moved to the dorms, so Midoriya has a bit of difficulty getting in to visit, so Todoroki helps with that. Midoriya exposes Endeavor for the asshole he is. Todoroki starts visiting his mother and using his fire. He comes with Midoriya to see Eri, and Midoriya comes with him to see his mother. Midoriya tracks down where his mom's grave is. Things continue in a sort of schedule for a while. Then Midoriya gets caught. Not even while doing his vigilante thing. It's when he snuck into UA to see Eri and Todoroki. It's half way through third year, he just finished visiting Eri (by himself this time), and before that he cuddled with Todoroki for a few hours.
But Nedzu changed something about his security that nobody was aware of, because Toga snuck into the school (not using somebody else's blood, surprisingly, but using hair dye and contacts with a UA uniform). So Midoriya gets caught trying to sneak back out of UA. He was wearing his vigilante costume because he went to UA directly after patrol. It's around 3:30 AM and Aizawa was woken up because that vigilante he's been trying to catch for months just tried to sneak out of UA. To sort this out and make sure nobody else has broke into UA, they shut down school the next day. Todoroki has a sneaking suspicion his dumbass vigilante boyfriend got caught. Eri doesn't understand why she's being guarded because the person who broke into UA was her big brother. When the situation is explained to 1A, Todoroki just facepalms and sighs. Everybody is questioned, and Todoroki is just like "Yeah, sorry about my boyfriend. He's clingy." They work out some sort of rehabilitation thing with Midoriya, and Aizawa and his husband (Yamada) are the ones given custody over him. At first Aizawa was reluctant to let Midoriya around Eri. Of course, Eri was going to be around Midoriya whether Aizawa liked it or not, because he leaves the room for five seconds to go find Eri, only to come back and see Midoriya bouncing Eri on his hip. Eri gives the simple explanation of calling Midoriya "Big Brother".
Aizawa is informed that Midoriya is the one who gave Eri to him to protect her, and that he's been sneaking into their home basically since the Overhaul arrest.