There's no way to tell exactly who the author would be. It could be a long - time fan of the original work that Issei is from. They might have had an idea for a story where they wanted to show a different side of Issei, one where he isn't as successful or powerful. Maybe it's someone who is exploring the idea of character development through a negative experience for Issei. It could also be a new writer in the fanfiction world who just thought it would be an interesting plot to write about Issei getting owned.
It could be any fan who is interested in creating a story around Issei's downfall. There are many amateur writers in the fanfiction community who might come up with such a concept.
The author could be a fan who has a particular view on Issei's character. They might see him as being a bit too cocky or over - confident in the original story and want to create a fanfiction where he is put in his place. Or it could be someone who is trying to explore different power dynamics in the fictional universe that Issei exists in. They might have noticed that there are not enough stories about Issei facing defeat and decided to write one. It could also be a group of fans collaborating to write this fanfiction, each bringing their own ideas on how to make Issei get 'owned'.
It could be about a character named Issei facing a situation where he is overpowered or defeated in some way. Maybe in a battle or a competition within the fictional world of the fanfiction.
Perhaps it could be a group of bullies from Issei's school days. They used to pick on him and now he's coming back to make them pay.
Well, it could be about Issei seeking revenge on those who wronged him in the past. Maybe someone bullied him or betrayed his trust, and now he's out for payback. He might use his unique skills or powers to get even.
Sadly, I have no idea who the author of 'issei is the darkness fanfiction' is. Fanfiction can be created by many different people all over the world, and without more context or research, it's impossible to determine the author.
One possibility is that there would be a great deal of conflict within the story's world. Other characters might be shocked and try to interfere. For example, some might think it goes against the natural order or the rules of their society.
It could be an amateur writer who is a huge Harry Potter fan and has a creative idea about Harry having a familiar. There are so many fans out there who like to write their own stories based on the wizarding world.
It could be a passionate fan who really loves the Ladybug universe and wanted to explore a different and more dramatic scenario. There are many amateur writers in the fan community who come up with unique ideas like this.
There could be consequences within the story itself as well. It might change the entire future arc of both Issei and Koneko in ways that are difficult to reconcile with the original character traits. For example, their relationship dynamics would be completely altered, and they would have to deal with the responsibilities of pregnancy, which could be a very different direction from what the original work intended. Additionally, other characters in the fanfiction might also be affected by this new development and their reactions could be hard to predict and write in a believable way.
Issei could react with anger. He might lash out at his partner and the person they cheated with. He could also become very confrontational, demanding explanations and apologies.
Sadly, without more details, it's difficult to determine the author of this fanfic. It could be a person who wrote it for personal enjoyment or to share with a small group of friends who also like Issei and dragon - related stories. It could be that the author uses a pen - name or is not well - known in the broader fan - fiction world.