It's possible that the child is an orphan Naruto found. Naruto, having known the pain of being alone as a child, decides to take the orphan under his wing. He brings the child back to Konoha to give it a home and a family within the village.
One possible plot could be that Naruto has been on a long and secret mission. During this time, he met someone and had a child. Now he returns to the village with the child, and the villagers are both shocked and curious. His friends, like Sasuke, might be initially skeptical but then come to accept the new situation. The child could also have some unique powers inherited from Naruto, which could lead to various adventures as they try to figure out how to control and develop these powers.
In this fanfiction, perhaps the child is Naruto's own. Maybe he had an adventure away from Konoha and met someone special. The child could be a symbol of his growth and newfound family. He returns to Konoha with the child to introduce it to his friends and show how he has changed.
The child could be an orphan from a far - off land that Percy visited. Maybe Percy found the child alone and starving, and felt responsible for the child's well - being, so he brought the child back.
His relationship with Hinata would be complex. If the child is his and someone else's, Hinata might be hurt at first but then, because of her kind nature, she would probably try to accept the child. With his friends, they would see him in a new light, as a father now. Sasuke might be more protective of Naruto and the child, given their past bond. And for the younger generation like Boruto, they would look at Naruto differently, seeing him as not just the Hokage but also a family man.
Well, one possibility could be that Percy has been on some sort of adventure and during that time, he discovers a child in need. He decides to take the child under his wing and brings the child back to his world. Then, he has to deal with the reactions of his friends and family, who are both surprised and a bit worried about this new addition.
In some fanfictions, Naruto might return to Konoha to a cold reception because the villagers still hold grudges from his past. Maybe they haven't fully accepted his power or the chaos he sometimes brought. For example, they could be afraid of his Nine - Tails power flaring up again and causing destruction.
It could be a child of one of Naruto's friends who passed away. For example, if Shikamaru died in a battle, Naruto might take in his child. Naruto would then try to pass on Shikamaru's wisdom and strategic thinking to the child, along with his own ninja skills.
In this fanfiction, the plot might involve Kushina coming back to help Naruto in his toughest battles. Maybe she uses her unique chakra abilities that Naruto has inherited to give him an edge. She could also provide emotional support, as Naruto has always longed for his mother.
Another theme is growth. Both Naruto and Hinata may have grown separately during Naruto's absence. When he returns, they have to adjust to the new versions of each other. For instance, Hinata might have become stronger in her own way, and Naruto has to recognize that.