Another plot could involve All for One somehow transferring a small part of his consciousness into Deku. Deku then has to battle with this foreign presence in his mind while trying to keep his friends and the world safe from the potential chaos it could cause. This would also lead to some interesting character development as Deku tries to resist the dark influence.
If Deku and All for One interacted, it could change the story drastically. For example, Deku might learn some dark secrets about the origin of One for All that All for One knows. This new knowledge could either make him doubt his path or give him new motivation to prove that his way of using power is right.
Their relationship in the fanfiction can be seen as a symbol of hope and inspiration. All Might represents the pinnacle of heroism, and by choosing Deku as his successor, he gives Deku the chance to fulfill his dreams. Meanwhile, Deku's determination and growth also inspire All Might to keep believing in the future of heroism, even in the face of his own declining power.
One common theme is power transfer. Since All Might gives Deku his power, this forms a central part of many fanfictions. Writers often explore how Deku copes with this new power and the responsibilities that come with it.
There's also 'Growth Together'. This fanfic shows how Deku and Todoroki support each other during tough times at UA. They face challenges not only from villains but also from within the school. Their relationship develops as they help each other overcome these obstacles.
One idea for a Deku's Quirk fanfiction could be exploring what would happen if Deku's quirk manifested in a different way. For example, instead of having to gradually control One For All, he suddenly has full mastery from the start. This could lead to a very different story arc where he is immediately seen as a top - tier hero - in - training, causing envy and admiration in equal measure among his classmates.
One idea could be a fanfiction where Deku's quirk suddenly mutates. Instead of just having One For All, he starts to develop an additional power related to it, like the ability to share a fraction of One For All's power with his friends temporarily to boost their own quirks in a time of great need.
There are fanfictions where Deku teams up with unexpected characters. For example, he might partner with a minor villain who has a change of heart. This creates interesting dynamics and new story arcs that deviate from the original plot but still stay true to Deku's character.