It could mean a fan - created story where Harry Potter is somehow related to the Grim Reaper. Maybe in this fanfiction, Harry has the powers or the role similar to the Grim Reaper, like being in charge of death in some way within the fan - made narrative.
One possible plot could be that Harry discovers he has the ability of a Soul Reaper. He then has to balance his life at Hogwarts with his new - found duties as a Soul Reaper. For example, he might have to deal with Hollows (evil spirits in Soul Reaper lore) that are lurking around the Forbidden Forest.
It could be that in the fanfiction, 'Don't Fear the Reaper' is a sort of mantra or a prophecy. For example, there could be a prophecy that a certain character will face a great danger symbolized by the reaper, but they are destined not to fear it and overcome it. It might also be related to the idea of sacrifice, where a character has to come close to death but not be afraid of it, in order to save others in the Harry Potter - like setting of magic, Hogwarts, and the battle between good and evil.
There's a fanfic called 'Potter, the Reaper's Apprentice' where Harry discovers his reaper abilities and has to navigate the magical and supernatural worlds at the same time. It's a great read because it combines the elements of both universes really well. It shows how Harry's Gryffindor courage helps him in his new role as a reaper, and also how his Hogwarts training gives him an edge when dealing with supernatural entities that are not strictly from the wizarding world.
The theme of fate also often comes up. The Grim Reaper is sometimes seen as a force that enforces fate, especially when it comes to death. In 'Harry Potter Grim Reaper' fanfictions, there could be a lot of speculation about whether the characters' fates are predetermined or if they can be changed in the face of the Grim Reaper. It can make for some really thought - provoking stories as the characters struggle against what might seem like an inescapable fate.
Well, it could be. The Harry Potter series is extremely popular and so is the idea of Soul Reapers in certain anime and manga. When you combine them in a fanfiction, it can attract the attention of fans from both sides. For example, some might be intrigued by how Harry Potter characters would interact with the powers and rules associated with Soul Reapers. However, it might not be mainstream popular but has a niche following.
In this fanfiction, it's possible that the Grim Reaper appears to Harry at a crucial moment, like when he's about to make a big decision. The Grim Reaper could show him different possible futures depending on his choices, much like a guide through the complex web of time and consequences. It could also be that the Grim Reaper has a connection to Voldemort, and Harry has to deal with this new and unexpected alliance or conflict.
Well, he might start using his wizarding skills in a new way. Maybe he'd use magic to make the process of guiding souls more efficient. He could also use his knowledge of the wizarding world to help souls that have some connection to it. For example, if there were souls of wizards who died with unfinished business in the magical realm, Harry could use his understanding of spells and potions to sort things out for them.
You can try searching on some popular fanfiction websites such as Archive of Our Own (AO3) or FanFiction.net. Just type in the exact title or related keywords and see if there are any stories that match.
There might be a new character introduced in the fanfiction who is using the appearance of the Grim Reaper to cause chaos. This character could be a dark wizard who has found a way to mimic the Grim Reaper's powers and uses it to spread fear among the wizarding community. Harry would then have to figure out who this impostor is and stop their evil deeds.