One idea could be the lone survivor Naruto having to navigate a world where all his friends have been put under a powerful genjutsu. He has to find a way to break the spell alone, facing many hidden enemies along the way.
One interesting idea could be the clash of different survival skills. The sole survivor might have unique ways of dealing with post - apocalyptic situations, and when they meet the lone wanderer, they could exchange knowledge on finding food or shelter. For example, the sole survivor could be good at farming in small, hidden areas, while the lone wanderer is an expert at scavenging in dangerous ruins. Another idea could be the exploration of different personalities. The sole survivor might be more cautious and reserved, while the lone wanderer is more adventurous and impulsive. Their meeting could lead to a lot of character development for both.
One plot idea could be that the lone wolf character, who might be an OC (original character), has a fateful encounter with Naruto. Maybe they start off as rivals, competing in a ninja mission. But as time goes on, they discover they have more in common than they thought and form an unlikely alliance. This could involve elements of mystery as the lone wolf's past is gradually revealed.
One idea could be a survivor in a post - apocalyptic world who has to deal with not only the usual threats like lack of food and water but also new, mutated creatures. Another could be a group of survivors on a deserted island where they discover a hidden, ancient civilization. Or perhaps a survivor in a war - torn city who forms an unlikely alliance with an enemy combatant to stay alive.
For the lone wanderer crossover fanfiction, a great plot could involve them crossing over into a world of superheroes. They might initially be seen as a threat but then prove themselves useful with their survival skills. They could also cross over into a medieval - like world and introduce new concepts of warfare. Another possibility is crossing over into a world filled with ancient, powerful artifacts, and they have to find a way to keep these artifacts from falling into the wrong hands.
One idea could be to have characters from different universes within the 'devil survivor 2' world meet and form unexpected alliances. For example, a group of normally opposing demon summoners having to work together to face a greater threat that endangers all of their worlds.
It could be a rogue ninja who has developed a new and extremely deadly jutsu. This ninja has a vendetta against Konoha and was able to take out most of the ninja there, leaving Naruto as the lone survivor.
Another plot could be that the lone rat discovers a long - lost relative of the cubs. This relative could bring both hope and trouble. The relative might have knowledge that could help the cubs grow stronger, but also attract unwanted attention from the rat's old enemies.
Another plot could involve Percy being sent on a solo quest in a completely different realm, like the realm of dreams. He has to navigate through the strange landscapes and face the nightmares that come to life. He could discover a connection between the dream realm and the Greek gods that no one knew before, which could change the way the demigods view their powers.
Well, you could have a survivor fan fiction where a contestant has a hidden skill, like being able to communicate with animals on the island. This could give them an edge in finding food and avoiding danger. Or perhaps a story where there's a traitor within the group, someone who is secretly working with the show's producers to create more drama. Also, a plot where the survivors find a map that leads to a hidden part of the island with a bountiful supply of food and shelter.
One idea could be exploring what would happen if a different character became the designated survivor. For example, a minor character from the show suddenly thrust into that role and how they would handle the political chaos.