One interesting concept could be the reversal of the power dynamics. For example, if Naruto was initially a villain or a very shy and introverted character instead of his usual energetic self. It would completely change the story's progression and his relationships with other characters like Sasuke and Sakura.
The plot could start with the reversed personalities or situations of the main characters. For instance, if Naruto is the cool and collected one while Sasuke is the hot - headed. Then, their goals might change. Naruto could be more focused on revenge or something dark, and Sasuke on bringing Naruto back to the light. This would create a whole new set of conflicts.
One possible plot could be that Sasuke, in the reversed role, is now the one trying to gain the village's recognition. He might be the underdog with a big dream, like Naruto originally was. He could be using his Sharingan in new ways to protect the village and its people, while Naruto, in Sasuke's role, has a more brooding and solitary nature, perhaps having left the village due to some past event and Sasuke is now on a journey to bring him back.
It adds diversity to the existing stories. By changing the gender roles, it gives a fresh perspective on the familiar characters and settings. Fans can explore different dynamics and relationships that might not have been as prominent in the original work.
In a 'Star Trek' reversed gender roles fanfic, the female characters could be the captains and lead the exploration missions, while the male characters serve as the ship's doctors or engineers. There are also fanfics in the 'Lord of the Rings' universe where female hobbits or elves are the ones on the grand adventures, taking the place of the male characters in the original story.
Perhaps in this fanfic, Astrid is the one with the mysterious past involving dragons. She has to hide her knowledge and connection to them from the rest of the village. Hiccup, being the popular and more 'normal' Viking, starts to suspect something about Astrid and eventually uncovers her secret, leading to a change in their relationship and the village's view of dragons.
A great plot could be that Sasuke, in the reversed role, is the village's hope. He is the one everyone looks up to. Naruto, with a dark past that led him to be bitter, is on a path of self - destruction. Sasuke tries to stop Naruto from causing harm to himself and others. He uses his own positive energy and the power of friendship to make Naruto realize that there is more to life than revenge. This would be a complete role reversal from the original Naruto and Sasuke dynamic.
A 'Naruto and Gaara Roles Reversed' fanfiction could start with Gaara being the one full of energy and constantly getting into trouble in the Leaf Village. He'd be eager to prove himself, much like how Naruto was in the original. Naruto from Suna would have to deal with the harsh treatment from his own village due to being the Jinchuriki. Their first encounter would be really interesting, as their personalities and circumstances are flipped.
Sasuke, in the reversed role, would develop in terms of his ability to forgive and his patience. He would have to be patient with Naruto's slow progress towards redemption. His character would become more about spreading hope and love in the face of Naruto's negativity. Naruto's development would be a long and arduous process. He would first resist Sasuke's attempts to change him, but as time goes on, he would start to see the error of his ways. His development would be marked by his struggle between his dark past and the new light that Sasuke is trying to show him.
One idea could be that Sasuke, in the role of the underdog, is constantly trying to prove himself in the village. He might be the one with a big heart, always reaching out to others. Meanwhile, Naruto could be the brooding loner who has a natural talent but is haunted by his past. For example, Sasuke could be the one to develop a new jutsu to protect the village, while Naruto is off on his own journey, slowly coming to terms with his need for connection.