In some fanfics, Naruto might team up with unexpected characters to defeat Pain. For example, he could join forces with Orochimaru. Orochimaru, with his knowledge of jutsus and dark arts, and Naruto, with his brute strength and positive energy, create a unique combination that outsmarts Pain's abilities.
One unlikely ally could be Zetsu. Zetsu is usually seen as a villain, but in a fanfic, he could have his own motives for helping Naruto defeat Pain. Maybe he wants to disrupt the Akatsuki's plans from the inside and sees Naruto as a useful tool for that.
Another plot twist might be that Pain has a hidden motive for attacking Konoha that is completely different from what was originally thought. And Naruto, in the process of defeating him, uncovers this truth. For example, Pain could be under the control of a more powerful enemy who wants to test Konoha's defenses through Pain's attack, and Naruto has to deal with this new revelation as well as defeat Pain.
Social media groups focused on Naruto can also be a good source. For example, on Facebook or Reddit, there are groups dedicated to Naruto. Members of these groups might discuss and share fanfictions they like. You can post a request for 'Naruto defeats Pain' fanfictions and see what kind of responses you get.
In this kind of fanfiction, there could be a lot of shock and disbelief among the characters at first. His friends might feel guilty for not noticing the signs earlier. They would probably become extremely protective of Percy.
The other students could have a range of reactions. Some might be sympathetic and try to befriend Harry more. Others might be afraid, especially if the abuser is still around. But overall, it would create a stir in the wizarding community, and there would be a general outpouring of concern for Harry's well - being.
She might be overjoyed. After all, Naruto is her son. She could immediately rush to find him and embrace him tightly, tears of happiness streaming down her face.
Well, one possibility is that Dark Naruto would be overjoyed. After all, Kushina is his mother. But at the same time, he could be very conflicted. His dark side might make him suspicious of her motives. He could test her in various ways to see if she's really who she says she is. And Kushina, on her part, would probably be heartbroken to see what her son has become.
His family member, if there is one in the story who is perceptive and caring. They might have seen some small signs over time but not fully understood what was going on. Once they find out about the abuse, their natural instinct to protect their family member would kick in, and they would be one of the first to react, showing concern and a determination to make things right for Percy.
Obviously Apollo himself. And the one he's in love with, who could be a nymph. Also, the other Olympian gods like Artemis, Apollo's sister, who might have a strong reaction to her brother's love affair.