Well, in DxD fanfiction, the Grim Reaper can be a really cool addition. It might bring a sense of dread and mystery. For instance, its appearance could be quite terrifying, with a dark cloak and a scythe. It could be that the Grim Reaper has a role in maintaining the balance between the living and the dead in the DxD world. And in some fanfictions, it may even have its own motives and goals, like trying to prevent a certain apocalyptic event that would disrupt the order of life and death.
Often as a menacing figure. With its signature scythe, it represents death. It may be shown as having a cold and indifferent attitude towards the characters in the DxD world. It just comes to do its job of taking souls without any emotion.
Another theme is the exploration of the afterlife. Given that reapers are associated with death and the afterlife, fanfictions often explore how the DxD world's view of life and death is affected by the presence of a reaper. They might show how the reaper's knowledge of the afterlife changes the perspective of the DxD characters.
One unique feature is the blend of two different mythologies. Highschool DxD has its own set of supernatural beings like devils, angels, and fallen angels. When you add the Grim Reaper concept, it creates a whole new set of interactions. For example, the Grim Reaper might have different views on life and death compared to the devils in Highschool DxD.
One popular Reaper DxD fanfiction is 'Reaper in the DxD World'. It has an interesting plot where the main character, a reaper, gets involved in the complex world of DxD. The story has great character development and some unique twists on the original lore.
Naruto himself is a very popular choice. His energetic and determined personality can bring a lot to a crossover story. Issei from DxD is also often included as he is a central character in his own series with his unique powers and his harem - like relationships. Another popular one is Sasuke. His cool and brooding nature contrasts well with the more flamboyant characters in DxD.
One possible plot idea could be a crossover where Naruto characters gain powers from the DxD universe and have to face a new, powerful enemy. For example, Naruto could learn about the Devil Pieces system and use it to strengthen his allies in Konoha. Another idea might be a story where a character from DxD ends up in the Naruto world and has to adapt to its ninja culture while also using their own unique abilities to help or hinder the existing power balance.
There's also 'Grim Reaper in Highschool DxD World'. In this fanfiction, the Grim Reaper character is inserted into the Highschool DxD setting. It focuses on how the Grim Reaper's presence changes the power dynamics and relationships within the school and among the different factions. It's full of action and some unique plot twists.
It might be an abbreviation for a name, like 'David X. Doe' or something similar. Or it could be a unique name within a specific group or community that is into fanfiction. Maybe it's a code name for a person who reviews fanfiction. Without more context, it's really hard to say for sure.
Here are some recommendations for novels about pirates, Naruto, and the Grim Reaper:
1. " One Piece: Death's Vice-Captain ": This novel tells the story of a person who obtained the Death System in the world of pirates and became stronger by crossing the heavens.
2. " The Shadow of the Fourth Generation of the Wood Leaf ": This novel was set in Naruto. The protagonist, Ember, was reborn in the Naruto World and began a series of wonderful adventures.
3. [Death's Strongest Ninja: The protagonist of this novel has the strongest fire-type sword, which can easily kill any enemy.]
4. Naruto: One Punch Town Security: This novel tells the story of a God in the Naruto World. It updates frequently.
Please note that the novels recommended above are all doujinshi novels based on the creations of One Piece, Naruto, and Death. The plot is novel and attractive, and it is worth reading.