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.
There could be a story where the daughter has some kind of medical condition that causes lap pain. Her dad, on noticing her discomfort, would be worried sick. He would likely do all he could to ease her pain, from getting her painkillers if appropriate to arranging for proper medical tests to find the root cause of the 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 For example, he could become withdrawn and isolate himself from his friends.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.
In Naruto future reaction fanfiction, characters might react to various things. For example, they could react to new jutsu developed in the future. They might be amazed at the power and creativity behind it. Maybe Naruto himself would be excited to see how the next generation has advanced the art of ninjutsu.
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.
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.
Jiraiya could be a great addition. Since he was Pain's teacher, his presence could add a lot of depth to the story. He could offer insights into Pain's past and also help Naruto understand Pain better.
I would recommend 'Pain's New Beginning'. In this fanfiction, Pain gets a chance to relive his life after a strange encounter. It has some really cool plot twists that keep you hooked. It also explores his relationships with other characters in new ways.
There could be. Fanfiction covers a vast range of ideas and concepts. Since Naruto has a huge fan base and Pain is a well - known character, it's not impossible for someone to have written a fanfiction where Naruto sings about Pain. However, it might not be a very common or mainstream idea, so you might have to dig a bit deeper in your search.