Another possibility is that he's being bullied. In school settings within fanfictions, bullying is a common theme. Percy might be trying to hide his face to avoid the taunts and mean looks from the bullies. He could be self - conscious about some aspect of his appearance that the bullies have targeted, like a scar or his overall look. By hiding his face, he hopes to protect himself from their cruel remarks.
One possible reason could be that he is on a secret mission and doesn't want to be recognized. He might be infiltrating an enemy organization or spying on someone. Another reason could be that he has some new power or mark on his face that he wants to keep hidden until he fully understands or masters it.
Sasuke could be one of the people who help him. Despite their past differences, they have a deep bond. Sasuke has his own skills and knowledge that could be useful in Naruto's situation, like his Sharingan abilities which could help in detecting enemies while Naruto is hiding his face.
His scar might make some people more intimidated by him. They could see it as a sign of his dangerous experiences and be a bit afraid to get too close. For example, new acquaintances in the fanfic might be hesitant to approach him at first.
On the other hand, Sasuke could be worried. He may think that Naruto is in some kind of trouble or danger. Given their history and the care they have for each other in the SasuNaru dynamic, Sasuke's concern could lead him to be more protective. He might start investigating the situation on his own to figure out why Naruto is hiding his face and ensure his safety.
In some fanfics, Percy's scar on his face could be a result of a betrayal. Perhaps a so - called ally turned on him during a mission. This person, who Percy trusted, secretly attacked him, leaving a scar on his face. This would add a layer of emotional depth to Percy's character, as he would have to deal with the pain of betrayal along with the physical reminder of it on his face.
For the bullies, if that's the case, his hiding of the face could either make them more determined to torment him or it could make them lose interest. If they see that they are getting to him, they might continue to pick on him. But if he seems to be shutting them out completely by hiding his face, they might move on to an easier target.
One possible reason could be that Naruto is hiding his face to conceal his emotions. In SasuNaru fanfiction, their relationship is often complex and full of unspoken feelings. Naruto might be afraid that Sasuke will read his true feelings if he shows his face. For example, if Naruto has developed deeper romantic feelings for Sasuke, he may not be ready to expose them, so he hides his face as a form of self - protection.
Perhaps he has hidden the full extent of his Sage Mode abilities. He might be able to stay in Sage Mode for a much longer time than he has shown so far, or have some other undisclosed powers within that mode, like the ability to sense enemies from much greater distances.
Well, he might face the challenge of leaving his mortal life behind. His relationships with his friends and family could be strained. He'd have to deal with new powers that are probably overwhelming at first. And he'd have to adapt to the politics and rules of the godly world which are likely very different from what he's used to.