Saruman met his demise in the novels when Gr铆ma, whom he had mistreated, took revenge and killed him. This shows that even those who were once under his control could turn against him when pushed too far.
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.
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.
You can start by looking on fanfiction.net. It has a large collection of various fanfictions, including those related to nazgul crossovers. Another place is Archive of Our Own (AO3). It's known for its extensive range of fan - created works and has a good chance of having some great nazgul crossover fanfictions.
It's the exploration of 'what if'. What if the Nazgul, these deathly wraiths, were to enter the world of Harry Potter? How would the characters react? Would they be able to use their magic against them? Fanfiction allows us to delve into these uncharted territories. We can see the Nazgul's influence on the already complex relationships in the Harry Potter series. For example, how would the Death Eaters view these new dark arrivals? It's all about the possibilities that open up when these two universes collide in fan - created stories.