Perhaps it's a world ruled by a tyrannical regime. People are oppressed, and there is no freedom of speech or movement. The fanfic might focus on a group of rebels trying to overthrow this regime and create a better world. They face many challenges, like being hunted down by the regime's enforcers and having to deal with internal conflicts within their own group.
It could be about a post - apocalyptic world where the environment has been so severely damaged that basic survival is a struggle. For example, there might be no clean water or breathable air, and the few remaining humans are constantly fighting over scarce resources.
It might be a world where a deadly virus has wiped out most of the population, and the remaining people have to deal with not only the virus but also the breakdown of society. There are no more functioning hospitals or government services. The survivors have to fend for themselves, form their own communities, and figure out how to avoid getting infected while also trying to rebuild some semblance of a normal life.
Survival. Given that the world is not fit to live in, characters will be forced to focus on basic survival needs such as food, water, and shelter.
In many fanfics, a world might be considered unlivable if it's full of constant war, extreme poverty, or widespread injustice.
Another theme could be survival. In such a world, characters would have to struggle to stay alive. They might face shortages of food, water, and shelter, and have to constantly fight off threats from other desperate people or dangerous creatures.
The challenges they face in this unfit world can shape their values. A character might initially value material possessions but, after seeing how meaningless they are in a world on the verge of collapse, come to value things like human connection and community. This transformation can be a key part of their development.
Maybe they live together as part of a witness protection - like situation in the wizarding world. Some powerful and dangerous wizard is after them, so they have to stay together in a hidden, magically protected house. They learn to live with each other's quirks, like Harry's impulsive heroics and Hermione's strict study schedules, and in the process, they strengthen their friendship even more.
Perhaps Fleur is a key part of a prophecy related to Harry's life. In this fanfic, it could be that without her presence and active participation in Harry's life, he will die. For instance, she might be the one who can unlock a hidden power within Harry that is necessary for his continued existence. Like she has to be with him at certain times or places to trigger this power.
It could be about a series of catastrophic events that are predicted to occur within a year that will end America. Maybe natural disasters start hitting one after another, like massive earthquakes and super - hurricanes.
One possible plot could be that Harry and Daphne start living together due to some sort of special arrangement. Maybe they are on a secret mission together and need to stay in the same place to keep an eye on things. As they live together, they gradually learn about each other's habits and personalities. Harry might discover Daphne's love for a particular type of magic or her unique skills in potion - making. And Daphne could find out more about Harry's past traumas and his true nature as a hero. They could start off as just roommates but slowly develop a deep friendship or even more as they face various challenges together.
He could be a mysterious outsider. Just suddenly appear in the Naruto world and start causing trouble. Maybe he's looking for something in the Naruto universe, like a powerful chakra source or a special jutsu. And the ninja have to figure out who he is and what he wants before he destroys everything.
In a fanfic, Naruto could fit into Hogwarts while protecting it in several ways. He could be introduced as a new kind of defender. His bright - orange jumpsuit might seem out of place, but his skills would speak for themselves. He could learn about the magic system quickly and use his chakra in ways that mimic magic. Maybe he could use his chakra to enhance the power of some Hogwarts' wards. Also, his friendly nature would help him make friends with students and teachers alike, which would make his integration smoother.