Well, if Izuku had a quirk in a fanfiction, he might be an even more formidable hero. He could have a quirk that combines elements of his original quirkless determination and a newfound power. For example, maybe he has a quirk that allows him to enhance the quirks of those around him while also having his own unique ability, like super strength. This would change the dynamic of his relationships with his classmates. He wouldn't be the underdog in the same way, and might take on a leadership role more quickly.
In a fanfiction where Izuku has a quirk, it could completely rewrite his origin story. Instead of being inspired by All Might in the same way, he might have a different hero that he looks up to, one who also had a similar quirk to his. His training would likely be different too. Maybe he wouldn't have to go through the intense physical conditioning that he did in the original story to make up for his lack of a quirk. His quirk could be something that gives him an edge in combat from the start, like the ability to teleport short distances. This would change how he approaches battles and his overall strategy.
His relationships would be different in many ways. With Bakugo, for example, Bakugo might not look down on him as much. Since Izuku would have a quirk, Bakugo might see him as more of a rival from the start. With his other classmates, they might interact with him more as an equal. Instead of being the one they all want to help, he could be someone who helps them with his quirk. For example, if his quirk was related to healing, he could be the go - to person when someone gets injured during training.
One great Izuku fanfiction is 'A Different Path'. In this story, Izuku gets a quirk that's not One for All but something entirely unique. It shows his journey of self - discovery and how he still manages to be a hero in his own way. The author does an amazing job of exploring Izuku's character and his relationships with other characters like Bakugo and All Might in this new scenario.
One idea could be that Izuku's quirk is related to time manipulation. He could use it to slow down time during battles, giving him an edge in combat. For example, he could dodge attacks with ease and plan his counter - attacks carefully.
The 'Underdog to Hero' trope is also common. Even when Izuku has a new quirk, he often starts off being underestimated. He has to prove himself not only to his classmates but also to the heroes around him. This trope is great for character development as we see Izuku grow in confidence and skill.
His relationship with Bakugo would likely change significantly. Bakugo might initially be jealous of Izuku's unique shadow quirk. But over time, they could develop a more competitive but respectful relationship, as Izuku's shadow quirk gives him new ways to fight. With his friends like Uraraka, Izuku's new quirk could make him seem a bit more mysterious. Uraraka might be curious about how his quirk works and they could bond over her trying to understand it.
His quirk could be something like 'Limitless Rage - Transformation'. When he gets angry, his body transforms into the Hulk form, growing in size and strength. The angrier he gets, the more powerful he becomes, similar to how it works in the Hulk's original story.
His relationship with All Might could become more of a partnership. With Izuku having his own quirk, they could team up to fight villains more often. All Might would no longer feel the burden of having to pass on his power, and Izuku would have more confidence in himself, leading to a more equal and collaborative relationship between them. For example, if Izuku's quirk was related to super strength like All Might's but in a different way, they could combine their powers in combat to defeat stronger enemies.
There are also fanfictions where Izuku's quirk has a hidden aspect. Maybe his connection to One For All unlocks memories or abilities from the previous users in a more profound way. For instance, he might be able to access the combat knowledge of the past users directly, almost like having an in - built combat instructor guiding his every move.
Well, if he was in the My Hero Academia world, his 'quirk' could be his super strength, flight, and heat vision all combined as one overpowered quirk.
One cool quirk idea could be 'Shadow Mimicry'. The user can blend into any shadow and move freely within the shadow realm, also being able to mimic the actions of those whose shadows they are in. It gives a lot of stealth and surprise attack possibilities in a fanfiction.