One possibility is that the fanfic focuses on the relationships Allen has in this new state. His friends might be confused or worried about him. For example, Lenalee could be trying to reach out to him, but Allen is pushing her away because he doesn't want to put her in danger. And the Order might be divided on how to handle Allen now that he's different. They could see him as a threat or as a potential weapon against the Millennium Earl.
Obviously, Allen would be one of the main characters since it's about his reversion to red. He's the center of this change and the one who will be experiencing all the consequences.
First, study the D Gray - Man world thoroughly. Know the rules, the characters, and the overall mood. For Red, understand their personality traits. Then, come up with an interesting plot idea, like a new mission for Red or a hidden past that's uncovered.
Definitely. It should be a continuation. Since there are still so many loose ends in the original story, like the full story behind Allen's transformation and the ultimate fate of the Black Order. 'D Gray - Man Remaining Story' will most likely carry on the story to answer these questions.
In D.Gray - Man fanfics, amnesia can be portrayed in various ways. Sometimes it's used as a plot device to create mystery. For example, a character might forget their past and their powers, leading other characters to search for the cause. This can add an element of suspense to the story.
One idea could be a story where Mana and the Earl have to team up against a common enemy that threatens their existence in ways they haven't faced before. This would force them to put aside their differences and use their combined powers.
In some fanfics, Allen might be depicted as dead, but it really depends on the specific plot and the author's creativity. Fanfic writers often take liberties with the original story, so there could be various interpretations.
There's also a fanfic called 'Red's Secret Allies in D Gray - Man'. It reveals some unexpected alliances that Red forms within the D Gray - Man world. The writing style is really good and it adds a whole new layer of intrigue to the existing story.
The D'Gray Man manga has indeed finished. It wrapped up with a satisfying ending that tied up most of the plotlines and left a lasting impression on readers.