Ok so there will be some changes to this as opposed to normal storyline. One of which is UA is a college school so everyone will at least be 20 in class A.

Izuku Midoriya(Portgas D. Izuku)

quirk: Flame Flame

Izuku can use the powers of the Flame Flame Fruit to turn his body into fire and manipulate it at will. Drawback is he cannot swim in seawater and if used too much, he can dehydrate himself.

One For All(self explanatory)

At the age of four, Izuku watched his father die during the war of the best at Marinefort. Ever since this day, Izuku was sworn by his mother to keep his powers a secret in fear for his own safety to even have him hold her maiden name to keep him from being in danger. He was also given during one of his last visits by his father his hat as a token of his visit. Though he agrees with his father's way of living with no regrets, Izuku wants to show he isn't a threat to the world and wants to do good. As such, he holds back a lot to the point he would easily be able to use OFA at higher percentages

Abilities:

Six Powers: Thanks to some training by a marine that was looking after the family, Izuku learned the six powers and has them down pact.

Haki: Izuku has Armament and Observation Haki down pact with some ability to user Conquerors Haki. He doesn't have much control of the last one however to only use it as a last resort.

Medical skills: Izuku has some knowledge in medicine to help those in need of it as well as some knowledge on transplants. He's smart, but dares not try to overstep a doctor if he can.

Izuku also has people in his life he holds in high regards though has no real connection to them by blood.

Monkey D. Luffy

Though he's never met his uncle in person, Izuku spent his time looking into him and learning everything he could about someone who was so close to his father. He had also asked his mentor for any information he could get about Luffy to a lot of time get caught up in the fights in Punk Hazard and Dressrosa.

Sabo

Just like Luffy, Izuku never met Sabo but knows as much as he can about him. He also learned of Sabo eating his father's Devil Fruit to the point he was happy it at least fell into the hands of someone Ace trusted when he was alive.

Monkey D. Garp

Izuku knows little about his great grandfather other than he's a hero with similar tendencies like him of sleeping while eating and eating everything in sight. He does know however that his mentor was given instructions by Garp to find him and Inko to keep them safe. Izuku can't respect the marine part of Garp, but he respects him as family and someone that wants to at least do the right thing.

Vice Admiral Smoker(White Hunter)

Izuku's mentor and protector. Smoker was asked by Garp to watch over both Inko and Izuku as a way of repenting for failing to save his grandson. The main reason he chose Smoker was because he knew how cruel the marines could be and wanted to save Izuku from the nightmare that he'd be put through for his lineage. Smoker for the most part finds Izuku a little annoying, but respects his will to do good to the point he tries his best to do what he can to help Izuku whether it's teaching Haki or the Six Powers, to having knowledge gained on Luffy and Sabo. Izuku sees Smoker as a fatherly figure and wants to be someone respected like him when he grows up.

Tashigi(will be 23 when Izuku's 20 with the parts where she was in the series being taken out or replaced) and G-5

Though he isn't a marine, the men respect him for wanting to do what he can to be a good person, but saw him as a problem when they found out he's the son of the pirate in the beginning. Tashigi on the other hand feels like Izuku constantly looks down on her to try and assert her age over Izuku with it being somewhat childish looking with Izuku making a game out of it. Though he messes with her, Izuku finds comfort between her and the men of G-5 to respect and care for them like family and wouldn't want anything bad to happen to them.

Monet(She's alive in this)

Izuku met Monet on Punk Hazard and was able to save her by making a transplant. After being brought onto G-5's ship, she woke up to be given two options. Try to live a better life with Izuku in hiding, or be arrested by the marines outside. She chose the first option to find some comfort in living with Izuku and Inko. Smoker doesn't trust her however with Tashigi not that far behind. Izuku did look into trying to save her little sister from Doflamingo to unfortunately come up empty. She was sad, but thanked Izuku for trying and works as a nurse in a hospital as a way to pay for staying with the Midoriyas.

Baby 5

During the hunt for Sugar on Dressrosa, Izuku stumbled upon her to start a fight. It somewhat ended with Baby 5 thinking he proposed to her and now follows Izuku like a loyal dog thinking that's what happened. Hearing about her, Izuku felt bad and asked Smoker to help for him to begrudgingly oblige. She helps Inko with cooking and cleaning as well as helps train Izuku in weaponry. She isn't allowed to go out alone though due to how naive she is for Monet to somewhat be dragged into watching her.

Alright. I think that's everyone for now. I might do this as a small harem with Monet, Tashigi and Baby 5 in it. What do you guys think? If it is, I'll do another bio chapter with the harem in like a week. Until then, I'm not putting any relationship tags up.