It could be a new character created specifically for this fanfiction. Maybe a powerful wizard who has been in hiding and uses the mask to conceal his true appearance while he moves around Hogwarts or the wizarding world.
Perhaps it belongs to a dark wizard who is trying to infiltrate Hogwarts or the Ministry of Magic. He uses the hollow mask to blend in and carry out his evil plans without being detected.
It might be related to a secret society or a dark magic object. In the Harry Potter universe, there are often mysterious items with special powers. The hollow mask could be one such item, perhaps used for disguises or to access hidden places.
The hollow mask could symbolize Naruto's hidden or repressed side. In fanfiction, it might represent a part of him that he keeps locked away, perhaps related to his past traumas or unacknowledged emotions.
It could be a powerful and mysterious shinobi. Maybe someone from an ancient hidden village who has been observing Naruto for a long time and decided to give him the mask as a test or a way to unlock his true potential.
Well, if Naruto got a hollow mask in fanfiction, he might gain new powers. The hollow mask could potentially enhance his speed and strength, like how it did for characters in Bleach. He could also use it to intimidate his enemies. Maybe it would give him a new form of chakra or a special jutsu that combines his ninja skills with the power of the hollow mask.
His combat abilities would likely be boosted. With the hollow mask, Naruto could have increased physical capabilities, such as stronger punches and kicks. His reflexes might also be enhanced, allowing him to dodge attacks more easily. He could potentially use the mask's power to disrupt his opponents' chakra or energy, similar to how hollows can disrupt spiritual energy in Bleach.
It could be an evil dark wizard. This wizard might have created the mask with the intention of using it for some nefarious purposes, like taking over the wizarding world. But before he could use it, the mask was lost or hidden, and now Harry has found it.
One common theme could be power struggles. The black mask and hollow elements might bring in new and powerful abilities, leading to characters fighting over them or trying to control them.
In some fanfics, Naruto might be able to use a hollow mask through some creative plot devices. Maybe it could be due to some sort of cross - over magic or a unique power - up he receives. However, this is completely a product of fanfiction and not part of the original Naruto lore.
It would be really cool. He might look really intimidating with the hollow mask on. And his fighting style could change completely, incorporating some elements from the concept of hollow masks, like maybe some dark - energy - based attacks.
One idea could be a character with the hollow mask bloodline having the ability to enter a shadow realm, similar to the Sharingan's genjutsu world. They could use it for stealth or to surprise enemies.