The child might be a descendant of an old and forgotten clan. Naruto discovers the child's unique abilities that are related to the clan's ancient techniques. He then takes on the task of raising the child to help the child control and develop these abilities while also giving the child a normal and loving childhood.
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.
One possible plot could be that Naruto discovers an orphaned child during one of his missions. He decides to take the child under his wing and raise it as his own. He would teach the child ninjutsu, just like Jiraiya taught him, and also instill in the child the values of hard work and loyalty.
The child could be an orphan from a small, destroyed village that Naruto comes across during one of his missions. This child might have lost their family to a powerful enemy and Naruto feels a sense of responsibility to take them in.
It could be a new character created by the author. Maybe someone who was born in a small, overlooked part of the village and has a power that is related to the prophecy but has been dormant until now.
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.
Maybe it's an adopted child. Naruto, with his big heart, could have taken in an orphan from one of the village's tragedies. This would give him the role of a single mother in a very unique way as he tries to instill his values and ninja skills in the child.
Sakura could be a main character. She might be the one who discovers the abandoned child and tries to figure out what to do. Kakashi could also be involved. He has a history with Naruto and might be torn between loyalty to Naruto and doing what's right for the child. Sasuke could be another character. He might return to the village and get involved in the situation, either to help or because he has his own motives regarding Naruto's actions.
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.
The child could be a prophesied one. In the world of Percy Jackson, prophecies are common. So, this child could be the one foretold in some ancient prophecy that is linked to Tartarus. Percy finding the child sets off a chain of events that will either save or doom the world. Maybe the child is the key to closing a portal in Tartarus that is releasing evil into the mortal world, and Percy is the only one who can help the child fulfill this great task.
The child could be a young demigod who got lost on a quest and ended up in Tartarus. Maybe they were trying to prove themselves and got in over their head.
Their child could inherit Naruto's blond hair and blue eyes, along with his never - give - up attitude. Maybe also get Samui's calm and composed nature. It could be a powerful ninja with a unique combination of skills from both parents.