A group of former war criminals who were pardoned but now want to take over the ninja world. They might have formed a secret organization during their time in prison or exile. They could be using new, dark jutsus that they developed in secret to try and overthrow the current leadership in the villages and establish their own rule.
Naruto is definitely one of the most popular. Since he's the hero of the war, many fanfics will focus on his post - war life, like his family life with Hinata and his role as Hokage. Sasuke is also very popular. His complex character and his journey of redemption in the post - war world are often explored. Sakura is another, especially her growth as a medic - ninja and her relationships post - war.
One idea could be focusing on the rebuilding efforts in the Hidden Villages. For example, showing how they come together to reconstruct the damaged infrastructure and restore relationships. Another could be about the new generation of ninjas growing up in a post - war world, dealing with the legacies and stories they've heard from the war. Maybe a fanfic about Naruto's role in maintaining peace after the war, like his diplomatic efforts with other villages.
Naruto and Tenten could interact through helping the village rebuild. Naruto would use his strength to move heavy debris, while Tenten would use her skills to organize and distribute the rebuilt ninja tools. In this process, they would exchange stories of the war and their hopes for the future of Konoha, gradually deepening their understanding and friendship.
One idea could be exploring how Naruto helps to rebuild the Hidden Leaf Village. He could use his influence to improve relations with other villages and start new trade agreements. Another idea is focusing on the relationships between the characters after the war. For example, Sasuke and Naruto's friendship could be further developed as they work together to ensure peace. Also, new characters could be introduced, like children of the main characters who inherit their powers and have to learn to use them in a post - war world.
One great 'Post War Naruto Fanfiction' is 'The New Era'. It focuses on how the characters rebuild their lives after the war. Another is 'Naruto: Post - War Reconciliation' which delves into the political and social changes in the shinobi world post - war.
There's 'Sasuhina: Post - War Bonds'. In this fanfic, Sasuke returns to the village and gradually forms a special bond with Hinata. It shows how they both deal with the traumas of the war while also exploring their new - found feelings for each other. It's really interesting to see how their relationship develops against the backdrop of a post - war world.
You can check out 'Harry's Struggle in Peace'. It's a fanfic that focuses on Harry's inner turmoil after the war. He's suffering from PTSD and has a hard time adjusting to a world without Voldemort. The fic shows his journey of trying to find meaning in his life again.
I would recommend 'Harry's Post - War Blues'. In this fanfic, Harry is not the triumphant hero everyone expects him to be after the war. He is constantly haunted by nightmares of the final battle and feels isolated even among his friends. The story shows how he slowly tries to heal himself with the help of some unexpected allies in the wizarding community.
One possible plot twist could be that Sasuke, now as a girl, has a different perspective on his past actions. Maybe he becomes more empathetic towards Naruto's ideals of peace. For example, instead of being so focused on revenge and power, he starts to see the value in building relationships within the village. Also, it could lead to some interesting romantic sub - plots, perhaps with Naruto or other characters having new feelings for Sasuke in this new form.