One possible reason could be for disguise. Maybe he is on a secret mission and doesn't want to be recognized easily. In the Naruto world, there are many dangerous foes, and wearing a face mask can help him blend in or hide his identity from those who might be targeting him.
Definitely Naruto himself. Since it's a Naruto face mask fanfic, he should be the central character. His friends like Sasuke and Sakura can also be included. Sasuke could be jealous of the attention Naruto's mask gets, or Sakura could be the one to patch up the mask when it gets torn in a battle.
One idea could be a fanfic where Naruto's face mask becomes a magical item. Maybe it has the power to hide his presence completely from enemies, leading to some really cool stealth missions.
One creative way to use a Naruto face mask in fanfiction is as a conduit for chakra transfer. Suppose a character is injured and another character uses the mask as a medium to transfer their chakra, kind of like how Naruto sometimes shares his chakra with his friends. The mask could have been specially designed for this purpose by a master ninja. Also, the mask could be a communication device. It has some sort of jutsu - powered technology that allows the wearer to communicate with other characters over long distances, just like how Naruto communicates with his allies during battles.
Well, obviously, the addition of the face mask gives him a more mysterious look. His usually open and friendly face is partly hidden, which might make others view him with more caution or curiosity.
One possible plot could be that Naruto discovers a special face mask with hidden powers. For example, it might enhance his senses when he wears it, allowing him to detect enemies from a greater distance. This could lead to new adventures as he has to figure out how to control and use these new powers while still being himself.
I'm not sure specifically what the 'Black Mask Hole Story' is as it could be something very specific or fictional. It might be a story related to a black mask and a hole in some sort of unique context, perhaps in a mystery or adventure plot.
Well, it could be about a character in Naruto who has a special mask that somehow gains a malevolent will of its own and starts to 'eat' the face as a metaphor for taking over the character's identity or abilities. Maybe it's a cursed mask that was once used in a forbidden jutsu.
Well, it's hard to say exactly without more context from the fanfic. But it could be that the mask is a sentient object in the story. In the Naruto universe, there are many strange and powerful items. This mask could be trying to take over the character's body by 'eating' their face as a way to gain control. It might also be related to a new enemy or a previously unknown power that the author has introduced.
Sasuke might be the main character. Since he's always on the hunt for power, he might come across this strange mask. And when the mask starts to 'eat' his face, it would be a test of his willpower and his ability to handle the unknown and dangerous forces that come with it.