Well, Naruto as a genie would be a really cool idea for a fanfiction. His character already has a strong sense of justice and a big heart. As a genie, he would be able to spread his positive influence even more widely. Imagine Naruto granting the wish of a poor village for food and resources. He could also use his genie powers to create illusions on a grand scale, fooling the enemies of the village. And his bottle or lamp (where he is trapped as a genie) could be hidden in some super - secret location in the Hidden Leaf.
Well, if Harry Potter becomes a genie in fanfiction, he could use his magic in very different ways. He might be able to grant wishes, which would be a huge change from his usual spell - casting. For example, he could grant the wishes of his friends like Hermione and Ron. Maybe Hermione would wish for all the knowledge in the world to be easily accessible, and Harry as a genie could make it so.
One thing that could happen is that Naruto's friends would be really surprised. Sasuke might be a bit skeptical at first, but then see the potential of Naruto's new powers. Naruto could grant Sakura's wish to become a better medical ninja by giving her some special genie - granted knowledge. His powers could also attract the attention of the Akatsuki, who might try to capture him to use his genie abilities for their own evil plans.
The story would change drastically. The whole dynamic of the wizarding world would be different. Instead of fighting dark wizards with spells, Harry would be dealing with the implications of being a genie. His relationships with other characters would shift as they would now see him as a being with the power to grant wishes.
A genie in a fantasy story can be a source of great mystery. It might have powers that are not fully understood at first. The genie could be from a different dimension or time. As the story progresses, the characters might discover that the genie has a connection to a prophecy or an important event in the past. This discovery could change the course of the story and the way the characters interact with the genie. For instance, if they find out that the genie was once a powerful wizard who was cursed into genie - hood, they might try to find a way to break the curse, which would add a whole new layer of plot to the story.
The genie might be a transformed wizard. Some powerful dark magic could have turned a wizard into a genie as a form of punishment. When Harry finds the lamp, he unknowingly releases this wizard - genie. This genie - wizard could have knowledge of magic that has been long forgotten, which could be very useful for Harry in his fight against Voldemort.
There could be a lemon merchant. This character might be a jolly fellow who travels around selling different kinds of lemons. He could get caught in the middle of the conflict between Jasmine and Jafar. Maybe he has some secret knowledge about the lemons that could help Jasmine defeat Jafar's plans.
Just say 'no' directly. Sometimes the simplest answer is the best. If someone asks you to be involved in Jafar fanfiction, a flat 'no' can be very effective.
One way could be simply stating that you don't like the character of Jafar enough to engage in fanfiction about him. For example, 'I'm not a fan of Jafar, so I won't be part of any Jafar fanfiction.'