A cool storyline could be that All Might and Izuku get trapped in a parallel universe where heroics are completely different. They have to find a way to get back while also learning from this new world. Another idea is that Izuku discovers a dark secret about All Might's past that makes him question their relationship but ultimately strengthens their bond as they work through it. Also, a story where All Might and Izuku team up with some of the villains to fight a greater evil that threatens the entire hero - villain ecosystem.
A more romantic storyline could also be interesting. Picture Izuku realizing his feelings for Itsuka during a school event. He might be shy at first, but his friends could encourage him to pursue her. Meanwhile, Itsuka might be oblivious at first, but as Izuku starts to show his true feelings, she begins to see him in a new light.
One great storyline could be Izuku spending his summer training with a new, secret mentor. This mentor could have a unique quirk that helps Izuku develop a new aspect of his power. For example, he might learn to control his One For All in a more precise way, like being able to focus it on just one part of his body for a short time. Another storyline could be Izuku going on a summer adventure with his classmates to a place full of rare quirks. There, they encounter various challenges and Izuku has to use his wits and strength to get them out of trouble. And finally, a story where Izuku discovers a long - lost relative during the summer who has some connection to his quirk and his family's past.
One interesting storyline could be Izuku and Melissa teaming up to create a new support item. Since Melissa is great at making support items in the 'My Hero Academia' world, and Izuku has a deep understanding of how quirks work. They might combine their skills to make something that helps Izuku enhance his quirk in a new way.
A really cool storyline could be a time - travel one. Izuku and Ochako go back in time and meet their younger selves. They have to guide their younger selves to become better heroes without changing the future too much. Along the way, they see how their past actions and decisions led them to where they are now. And this experience also makes them realize how important they are to each other in their present lives.
One possible storyline could be how Female Izuku deals with her pregnancy while still trying to maintain her hero training. Maybe she has to find new ways to use her quirk safely for the sake of the baby.
One great example could be a fanfic where Izuku gains Wolverine's healing factor. This would completely change the dynamic of his battles in the My Hero Academia universe. He could be more reckless in combat, knowing he can quickly recover. Another example might involve Izuku learning Wolverine's combat style, which is very aggressive and up - close. This could add a new layer to his fighting techniques and make him a more formidable opponent.
There could be a fanfiction where Melissa and Deku are paired for a school project at U.A. High. They initially have different ideas but gradually learn to work together. During the project, they discover a hidden danger within the school that is related to a new type of quirk - erasing device. Together, they have to find out who is behind it and stop it before it affects all the students.
Another storyline could be a training arc where they help each other improve their skills. Shouto might teach Momo how to better handle high - pressure situations, while Momo could teach Shouto how to be more creative with his quirk usage. This could lead to a stronger bond between them as they grow both as individuals and as a team.
Well, if All Might and Inko got together, Izuku would likely be overjoyed. He idolizes All Might, and having him as a father - figure would be a dream come true. It could also give Izuku more direct access to All Might's knowledge and training, which would make him an even more powerful hero in training.
In some fanfictions, their relationship might develop more quickly. For example, All Might could reveal his true form to Izuku much earlier, leading to a deeper bond right from the start. This could make Izuku more determined to prove himself worthy. In other cases, their relationship could be strained. Maybe Izuku starts to doubt All Might's methods and they have a falling out, only to reconcile later when they realize they both have the same goal.