Well, in a fanfiction scenario, Harry Potter might use his powerful magic like the Patronus charm. The Patronus, being a powerful positive force, could potentially drive away the Nazgul which are associated with darkness and fear.
The Shadows of War Nazgul stories are mainly about the dark and menacing Nazgul in the game's lore. They are powerful servants of Sauron, and the stories might cover their origin, their powers, and their role in the war.
The Nazgul were once men. They were corrupted by the power of the Rings of Power given to them by Sauron. These men, kings, sorcerers, and warriors in their former lives, became his most feared servants. Their back stories involve their initial allure to the power of the rings and their gradual descent into darkness under Sauron's influence, losing their humanity bit by bit until they became wraith - like beings, bound to Sauron's will.
He could meet Frodo. Frodo is a very important hobbit, and Aragorn might have an interesting conversation with him about the Ring and their different experiences.
Aragorn may develop a more complex relationship with power. As the Ringbearer, he has to constantly battle the allure of the Ring's power. This could lead to him becoming more humble as he realizes how easily power can corrupt, even someone as strong - willed as him. He might also grow in his understanding of the smaller races, like the hobbits, who he now has a new - found respect for since he is in a position similar to Frodo's.
Talion might be in awe of Aragorn at first. Aragorn is a well - known figure in Middle - earth, a rightful king. Talion, being more of a lone warrior, could look up to Aragorn's leadership. Aragorn, on the other hand, would likely be cautious yet curious about Talion. He might question Talion's methods which are different from his own. But as they get to know each other, they could develop respect for each other's skills.
One idea could be a Nazgul crossover with the modern world. Imagine the Nazgul appearing in a big city, causing chaos among the unsuspecting population. Another could be a crossover with a fantasy realm like Narnia, where the Nazgul's dark presence contrasts with the more magical and positive elements of Narnia. A third idea is a crossover with a superhero universe, and the heroes have to figure out how to deal with the Nazgul's otherworldly powers.
One interesting Harry Potter and Nazgul fanfiction could be one where the Nazgul somehow cross into the Harry Potter universe. Maybe they are drawn there by the dark magic that Voldemort wields. A great place to start looking for such fanfics is on fanfiction.net. There are many works that blend different fantasy elements together in creative ways.
One of the most important aspects is their fall from grace. They were once men of some standing, but through their greed for power via the Rings of Power, they became slaves to Sauron. Another aspect is the way their physical and mental states changed. Their once - human forms deteriorated into something more sinister, and their minds became completely dominated by Sauron's will.