Naruto for sure. And Sasuke might also be in it. They could have a rivalry even on the deserted island, like competing to see who can make the best use of the lemons. Kakashi could also show up as a sort of guide or mentor figure, teaching them how to survive with the resources available, especially the lemons.
Obviously Naruto would be one of the main characters. Sakura could also be there. She could use her medical knowledge to figure out if the lemons have any special healing properties.
The main character would be Naruto. But there could also be some new characters created specifically for this fanfic. For instance, an old hermit who has been living on the island for years and has a deep understanding of the lemon trees. This hermit could teach Naruto about the secrets of the lemons, like how they can be used to boost his chakra or communicate with certain animals on the island. There could also be a group of bandits who are after the valuable lemons, and Naruto has to protect the island and its lemon resources from them.
A possible plot for this fanfic could involve Naruto being teleported to a deserted island which has an abundance of lemon trees. As he tries to figure out how to get back home, he starts to experiment with the lemons. He might find that the lemons have some sort of energy that he can harness. This could attract the attention of some local island spirits or creatures. Naruto then has to use his ninja powers and the power of the lemons to either befriend or defeat these beings in order to find a way off the island.
He could meet a lost shinobi from a different village. This shinobi might have been stranded there for a long time and has some valuable knowledge or skills that Naruto could learn from.
Another idea for the Naruto deserted island fanfic is that Naruto is sent to the island as a form of training. He initially struggles to adapt to the harsh environment. However, as time passes, he learns to control his chakra in new ways, perhaps by using the natural elements of the island. He could also meet a hermit on the island who teaches him some unique ninja techniques.
A lemon - themed ninja from a far - off land could be introduced. This ninja could have powers related to lemons, like being able to shoot acidic lemon juice as an attack or use the peel to create a shield. He might initially be hostile towards Naruto but later become an ally.
The main characters could be a group of friends who were on a boat trip and got shipwrecked. They might be from different backgrounds, like one could be a good fisherman which helps them get food, another might be good at building things and is in charge of making shelters.
One possible plot could be that Naruto is stranded on a deserted island and discovers a strange lemon - like fruit that gives him unique powers. He then has to figure out how to survive on the island while also dealing with the strange effects of the fruit.
There's a chance it could be a spirit of some sort. In the Naruto world, there are many spiritual elements. A spirit that has been bound to the island for ages could appear to Naruto. This spirit could guide him to hidden treasures or teach him some ancient ninja wisdom that has been lost in the modern ninja world.
It could be a powerful rogue ninja who has made Zacks Island his lair. He might be hoarding some valuable resources on the island and sees Naruto as a threat to his plans.
Obviously, Naruto would be one of the main characters since it's in the title. There might also be characters from Naruto's original world who are either helping or opposing him in his revenge plan. And the 'lemon' part might suggest a female character who has a special relationship with Naruto, like Sakura or Hinata perhaps.
Well, of course, the babysitter would be one of the main characters. She could be a young girl, maybe in her late teens or early twenties, who is trying to earn some extra money while also dealing with her own personal issues.