The interaction between Harry's ghost and Naruto's seal in this fanfiction could be really complex. Harry's ghost might initially be confused when it ends up near Naruto's seal. It may not understand the nature of the seal at first. However, as it observes, it might notice the flow of chakra within the seal. If Harry had some knowledge of sealing magic in his own world, he might try to compare it to what he sees in Naruto's seal. His ghost could also potentially be a catalyst for some change in the seal. Maybe it causes the seal to react in a way that it has never reacted before, which could either be a good or a bad thing depending on the context of the fanfiction.
One consequence could be that it disrupts the balance of chakra within the seal. This might lead to Naruto having some issues with his power control or even cause the seal to weaken or malfunction.
Well, perhaps in the moment of Harry's death, a powerful dark magic from the Harry Potter world collided with a strange space - time anomaly in the Naruto universe. This catapulted his essence into Naruto's seal. Inside the seal, Harry could be a source of new wisdom for Naruto. He could teach Naruto about things like loyalty and sacrifice from his own experiences. And he might also gain some of Naruto's positive traits, like his unwavering determination, which could help him in his new 'afterlife' within the seal.
He could develop the ability to use chakra. Since he's in the Naruto universe now, he might figure out how to manipulate chakra using his magical intuition. Maybe he could combine his Patronus charm with chakra to create a new kind of protective shield. Also, he could learn to move at high speeds like Naruto characters do, which would be a new ability for him considering he was mainly using apparition in his own world.
Harry could try to communicate with the entities in the seal. By making allies, they might help him survive. For example, if he befriends a chakra - based spirit, it could guide him on how to get the resources he needs, like food (in a spiritual sense perhaps) or a safe place to stay within the seal.
The Ghost Seal was an artifact in the book Grave Robber's Chronicles written by the third uncle of the Southern Sect. It was said to belong to King Shang of Lu. The Ghost Seal had the ability to command Ghost Soldiers, which were Blood Corpse Soldiers created by the Queen Mother of the West. The Ghost Seal also had the ability to open the Ultimate Bronze Door. The person who held the Ghost Seal could use the Ghost Soldiers to fight. However, the details and quantity of the Ghost Seals were not mentioned in the article.
In many fanfictions, Naruto might use his unique chakra, perhaps enhanced by his Uzumaki heritage or the Nine - Tails' power. His strong will and connection to his friends could also play a role, allowing him to find a way to break the seal through sheer determination and his belief in Neji's potential.
If Harry is stuck in Naruto's seal in fanfiction, he could potentially discover new forms of energy or power. Since he's used to magic, being in the seal might expose him to different types of energy like chakra in a very direct way. He could also make friends with the entities inside the seal, who could teach him things about Naruto's world that he would never have known otherwise. This could give him an edge when he finally gets out of the seal and has to interact with Naruto and the others.
The Karma Seal can change Naruto's appearance. In some fanfictions, it might give him a more menacing look with strange markings spreading across his body.
There could be a situation where an ancient technique is awakened within Hinata. This technique might have been long forgotten, but due to certain events in the fanfiction world, it resurfaces. This ancient technique could be the key to her being able to control Naruto's seal. It might involve her chakra nature or some spiritual connection she has with the seal's origin or the entity that placed the seal on Naruto in the first place.
The curse seal often gives characters increased power. For example, they might become stronger physically, able to take on tougher opponents. In some fanfiction, it can also change their appearance, like making their eyes glow or their skin take on a different hue.