One interesting plotline could be Izuku using his reality - controlling powers to create a world where everyone has equal opportunities in the hero world, regardless of their quirks or background. He might rewrite the rules of hero society to make it more inclusive and fair.
In some fanfictions, Izuku could use his power to enter alternate realities. He might find himself in a reality where he never got his quirk, and see how different his life would be. This could lead to him learning more about his own identity and the importance of his original quirk, and then using his reality - controlling power to merge the best aspects of different realities into his own.
Ochaco Uraraka could also be a common pairing. Since she has her own insecurities and dreams in the hero world, Izuku's reality - controlling power could play a role in either helping her achieve her goals or creating new challenges for their relationship. For example, if Izuku accidentally changes something in reality that affects her family's financial situation, it could impact their relationship and how they interact.
One possible plotline could be Izuku having superhuman abilities that are not like the normal quirks in the original story. For example, he might have the ability to manipulate time or space in ways that are completely unheard of in the My Hero Academia universe. This could lead to him being both feared and revered by others.
One possible plotline could be Izuku using his knowledge of Pokemon to help him in his hero training. For example, he might study how Pokemon use their unique abilities and apply similar strategies in combat against villains.
One possible plotline could be Kaguya using her powers to manipulate Naruto into fighting his friends. She might twist his perception of right and wrong, creating chaos in the ninja world. Another could be Kaguya trying to use Naruto as a vessel to regain her full power and reshape the world according to her will.
One possible plotline could be Naruto using his newfound control over silver to create unique jutsu. Maybe he can shape silver into weapons or shields in the heat of battle, giving him an edge against his foes.
Well, in some fanfictions, Harry might control the Dursleys by making them understand the wizarding world. He could show them magical things and, as a result, they start to respect him and his abilities. This could lead to a whole new dynamic in the household, where the Dursleys are no longer mean but rather in awe of Harry and his magic.
Well, in some fanfictions of this kind, Izuku as a girl might discover new aspects of her Quirk. Since the physical change could potentially affect how she uses her power. Also, there could be a plotline where she has to deal with romantic interests in a new way. As a girl, she might attract different kinds of attention from her male classmates, and she has to navigate through those new feelings and situations.
One possible plotline could be Izuku's struggle against the forced heroism, like trying to find his own identity within the constraints. Maybe he starts to question the true meaning of being a hero when it's forced upon him.
One interesting plotline could be their journey in starting a family. They might face challenges like Izuku's hero duties interfering with family time, but they work through it together. Another could be them renovating their first home as a married couple, with Ochako having creative ideas and Izuku using his strength to help.
Well, in some izuku growth quirk fanfiction, a great plotline is when Izuku has to hide the full extent of his growth quirk. Maybe because it's too powerful and he doesn't want to attract the wrong kind of attention. This could lead to some really tense moments where he has to use it subtly to save the day without revealing his true power. Also, there could be a plotline where his growth quirk is tied to his emotions, so he has to learn to control his feelings to master his quirk.