Well, one possible plot could be Naruto coming back to the village and being hailed as a hero. He might then focus on rebuilding the parts of the village that were damaged during the Pain attack. He could also start training the next generation of ninja, sharing his newfound wisdom and strength.
In this kind of fanfiction, Naruto might be welcomed as a hero. The village could start to rebuild with his leadership. People would look at him with newfound respect and admiration.
I'm not sure which is the absolute best, but 'Naruto and the Spectacle of Pain's Battle' is another one that stands out. It has some unique interpretations of the fight, like how Naruto analyzes Pain's techniques in real - time and how that affects his own future battles. The writing style is engaging and it keeps you hooked from start to finish.
It could be a rogue ninja from another village who sees Naruto's victory as a threat to their own plans. Maybe they were planning some sort of takeover or power play and Naruto's new - found status throws a wrench in their plans.
One great fanfiction could be 'Naruto's Ascent Against Pain'. It really delves into Naruto's mindset during the fight and adds some unique jutsu concepts. Another is 'Beyond the Pain Battle', which focuses on the after - effects of the fight on the village and Naruto's relationships. There's also 'Naruto vs Pain: The Alternate Path' that takes a different turn in the fight's progression.
You can try searching on fanfiction websites like FanFiction.net or Archive of Our Own. They usually have a wide range of Naruto fanfictions, and you might be able to find one about Naruto watching the fight with Pain there.
The biggest difference is the creativity of the fanfiction writers. In the anime, the fight follows a set storyline. But in fanfiction, anything can happen. For example, Naruto could suddenly gain a new power that was never in the anime. It's like a whole new world of possibilities.
One possible plot development could be Naruto focusing on rebuilding Konoha. He might use his newfound influence and power to inspire the villagers and make Konoha stronger than ever. Maybe he starts new training programs for the ninja of the village to better prepare them for future threats.
Well, FanFiction.net is a great place to start. There are thousands of Naruto fanfictions there. Just type in 'Naruto fight Pain' in the search box and you'll get a bunch of results. Another option is Archive of Our Own. It has a more organized tagging system, so you can find relevant fanfictions more precisely. Some Naruto - focused forums might also have links to such fanfictions shared by fans.