In a 'naruto on island fanfiction', Naruto might find himself on an island that is constantly changing its geography due to some sort of powerful and unstable ninjutsu. This would force him to constantly adapt and use his ninja skills in new ways. He could also meet a spirit or entity on the island that claims to know his destiny and he has to decide whether to trust it or not. There could be a race of people on the island who are immune to normal ninja attacks and Naruto has to learn their ways to be able to defend himself and communicate with them.
Maybe the island has some sort of magic that makes the women on it more attracted to Naruto. For example, it could be a chakra - related magic. As Naruto tries to figure out how to leave the island, he has to deal with the complex relationships that are developing among him and the female characters, like Sakura, Hinata, and Ino.
One idea could be Naruto and Tsunade getting stranded on the island and having to work together to survive. They might discover some ancient secrets or powers on the island.
One idea could be that Naruto finds himself mysteriously transported to Total Drama Island. He could use his ninja skills in the various challenges, like using his speed to win races or his shadow clone jutsu to complete multiple tasks at once. Another plot could involve the Total Drama Island contestants being sent to the Naruto universe and having to adapt to the ninja way of life, facing off against ninja enemies with their own unique skills.
Well, a great plot for a 'Naruto Zacks Island' fanfic could involve Naruto being sent to Zacks Island for a special training mission. On the island, he discovers an ancient prophecy related to his Nine - Tails power. He has to work with the local inhabitants, who are initially skeptical of him, to fulfill this prophecy and in the process, he learns new techniques and gains a deeper understanding of his own power.
One idea could be a human character getting lost on Monster Girl Island and having to form alliances with different monster girls to find a way back home. Each monster girl has her own unique abilities and personalities, like a mermaid - like monster girl who can help navigate the island's waterways.
One idea could be that a mysterious ship arrives on the island, but it turns out to be a time - traveling vessel. The castaways have to decide whether to take the risk and go with it to a different era. Another could be that Gilligan discovers a hidden cave filled with strange artifacts that seem to have magical powers. They could then use these powers to try and finally get off the island.
Perhaps Percy is banished with some of his friends, and they have to build a new society on the island. There could be internal conflicts as they struggle to adapt to their new situation and different leadership styles emerge. Percy has to navigate these relationships while also finding a way to get back home and clear his name if he was wrongly banished.
One idea could be a human having to form alliances with different monsters to survive a natural disaster on the island. Another could be a human using their knowledge to teach the monsters new skills in exchange for protection. Or perhaps a human discovers a hidden power within themselves while on the island and uses it to gain respect among the monsters.
One idea could be a character who was previously eliminated getting a second chance and having to prove themselves all over again. Maybe they have some new skills or a changed attitude.
A plot idea could be that Naruto discovers a new, ancient form of chakra that has been lost for centuries. He then has to train to master this chakra while also dealing with the political implications within the Hidden Leaf Village. Some elders might be against him exploring this new power for fear of the unknown, but Naruto, being Naruto, is determined to master it for the good of the village.