His fighting style could become more aggressive. Without the fear of pain, he might be willing to use more extreme techniques that would otherwise be too dangerous because of the pain they cause to the user. He could push his body to the limit more often.
It could also lead to changes in the power dynamics. Without Naruto, Akatsuki might see the Hidden Leaf Village as an easier target. However, the village could also discover new heroes among the younger generation. The remaining characters would have to find new sources of inspiration and strength.
One possible plot development could be Naruto's internal struggle with the newfound power and responsibility. He might start to question his own limits and how to better protect the village in the future. Another could be the rebuilding of Konoha. Naruto could be deeply involved in the restoration efforts, both physically and mentally, trying to bring back the hope and strength to the villagers.
Mentally, it would be a huge blow to the ninja community. Naruto inspired many with his never - give - up attitude. His death might make some ninjas lose faith in their own abilities and the future. But on the other hand, it could also fuel the determination of some to become stronger in his memory.
Sakura could play an important role. She might be more concerned about Naruto's well - being after such a tough fight. She could also use her medical skills to help in the rebuilding of Konoha. Kakashi, too, could be significant. He could guide Naruto in understanding his new powers better and also contribute to the village's security plans.
In many fanfictions, Naruto might use new jutsus or a deeper understanding of his own power. Maybe he taps into a more powerful form of the Nine - Tails' chakra and combines it with his Sage Mode in a unique way to overpower Pain.
In some fanfictions, Naruto's pain might manifest through his actions. For example, he could become withdrawn and isolate himself from his friends. This is because Naruto has always been a social person, so any deviation from his normal behavior could be a sign of his internal pain.
One possible cause could be his sense of failure. Naruto always wants to protect his friends and village, so if he fails in a mission or is unable to save someone, it can cause him great pain.
Konan could be really interesting. In some fanfictions, she might have a different backstory or motivation that affects the Naruto vs Pain fight. For example, she could be secretly trying to stop Pain from going too far in his destruction of the Leaf Village.