The story could develop in a very dark direction. Sasuke might be filled with regret immediately after killing Naruto. This could lead to him isolating himself from the rest of the ninja world as he grapples with his actions. The ninja villages might be in chaos as Naruto was seen as a symbol of hope. Without him, there could be power struggles among different groups.
After Naruto's death by Sasuke's hands, the story could take a turn towards exploring the consequences on a global scale. Other nations might see this as an opportunity to invade the Hidden Leaf Village. Sasuke, now alone, might have to face these threats while also dealing with his inner demons. Meanwhile, characters like Sakura and Kakashi would have to step up in new ways, filling the void left by Naruto. It could also lead to the discovery of new powers or alliances as everyone tries to adapt to this new, darker world.
The Hidden Leaf Village would surely launch a rescue mission. This would involve characters like Kakashi, Sakura, and the other ninja. Their efforts to find Naruto would be a major part of the story. Meanwhile, Sasuke might be moving Naruto from one location to another to avoid being caught, which would add more twists and turns to the plot.
Sakura would be devastated. She has deep feelings for both Naruto and Sasuke. She might turn against Sasuke completely and try to take revenge herself. Kakashi would be in shock. He has mentored both and would likely feel like he failed in some way. As for the other ninja from the Hidden Leaf, they would be angry and mournful at the loss of their hero Naruto.
Their relationship could start with respect. Naruto has always respected Sasuke, and in this case, Fem Sasuke. After the war, they might start having conversations about their dreams for the future. This could lead to them spending more time together, like having dinners or just walking around the village. Eventually, they realize they have feelings for each other.
One possible scenario could be a power imbalance. Maybe Sasuke discovers some new, extremely powerful jutsu that Naruto has no defense against. For example, a jutsu that can nullify Naruto's chakra or attack his spirit directly. Another possibility is a miscommunication or a breakdown in their relationship. If Sasuke believes Naruto has betrayed him in some way, his anger could lead him to kill Naruto. However, this goes against the core of their bond in the original series.
Naruto would be shattered. Given his strong sense of justice and his connection to Hinata, whether it's a romantic or platonic one. He would initially be numbed by the shock. But soon, his emotions would erupt. He could go through different stages, from mourning and self - blame (thinking he could have protected her) to a fierce determination to make things right. His actions would be driven by his love and respect for Hinata, and he would not rest until he has either avenged her or found a way to bring her back, if possible.
If Naruto gets killed in a fanfiction, the storyline would change drastically. Konoha would lose its most powerful shinobi and its symbol of hope. His friends like Sasuke, Sakura, and Kakashi would be deeply affected. Sasuke might go on a rampage seeking revenge. The village would be in a state of shock and mourning, and its defenses would be weakened. Enemies might see this as an opportunity to attack.
The story might start with Naruto arriving at Hogwarts as Harry. He would be the famous 'Boy Who Lived' but with his ninja - like instincts. Sasuke as Ron would be initially a bit standoffish but gradually grow closer to Naruto. They would face the challenges of Hogwarts together, like dealing with the dark magic threats. Naruto's ability to think outside the box as a ninja could lead them to find unique solutions to magical problems.
The development would be quite complex. Naruto, taking on Sasuke's life, would be more in tune with the darker side of the ninja world. He might struggle with the coldness that Sasuke often showed but also use his own warmth to thaw some of the Uchiha's colder relationships. Sasuke in Naruto's position would have to adapt to Naruto's simple yet powerful dreams. He could use his Uchiha abilities to make Naruto's dream of becoming Hokage more achievable in a different way. Also, their battles against common enemies would be very different as they would approach them from each other's perspectives.
Sasuke's development would be complex. He might start to question his entire ideology that led him to kill Naruto. He could become more empathetic towards others as a result of his regret, realizing the value of life that Naruto always represented. He might also try to make amends in the ninja world, but it would be a long and difficult journey as he has to deal with his own guilt.
Sakura might develop into a more confident and assertive person. After the war, she has proven herself as a strong kunoichi, and with Sasuke by her side, she could grow even more. Sasuke, on the other hand, would develop by learning to trust and love again. He has been through so much, but with Sakura's love and support, he could become a more stable and caring person.