Gray could be one. Since he and Natsu have a long - standing rivalry, Gray might try to bring Natsu back to Fairy Tail. He'd be conflicted between his annoyance with Natsu and his concern for his former guildmate.
One popular 'natsu is dark fanfiction' might be those that explore Natsu's inner turmoil in a more sinister way. For example, a story could depict him being corrupted by a dark magic that changes his personality. He might become more aggressive towards his friends, not out of true malice but because of the influence of the dark power. This can create a lot of conflict and drama within the Fairy Tail universe.
The main characters are obviously Natsu and Mirajane. Natsu, who has a dark side in this fanfiction concept, is known for his fiery magic and impulsive nature. Mirajane, on the other hand, is a powerful mage with her demon form capabilities.
Well, one possible plot could be that Natsu, after some sort of betrayal in Fairy Tail, decides to create his own dark guild. He might gather some disgruntled mages who also feel wronged by the mainstream guilds. Their goal could be to change the magic world's power structure in a more radical way, using darker forms of magic that are usually shunned. For example, they could explore ancient and forbidden magic spells to gain an edge over other guilds.
One great 'Dark Natsu Time Travel' fanfiction is 'Time's Twist'. It takes Natsu on a journey through different time periods in the Fairy Tail universe. The story is full of action as Dark Natsu battles foes from various eras. Another interesting one is 'Journey Through Time with Dark Natsu'. It focuses on how Dark Natsu's presence changes the course of history in the story.
One interesting 'dark natsu and mirajane fanfiction' could be where they team up to face a powerful dark magic threat that has been plaguing the guild. In this story, Natsu's dark side might be triggered by the intensity of the magic they are up against, and Mirajane has to use her demon form to keep him in check while they fight side by side.
First, you need to understand Natsu's character well. Think about what could realistically push him towards the dark side. It could be a great loss, like the death of a very close friend. Then, plan out how this change will affect his relationships. For example, will he still care about Lucy in the same way? Next, create a new conflict that is related to his dark state. Maybe the guild has to decide whether to fight him or try to save him.
In this fanfiction, the characters would have to adapt to a more cutthroat environment. Natsu's friends from Fairy Tail who might join him in the dark guild would struggle with their new identities. They would have to learn to use magic in more aggressive and unorthodox ways. Their moral compasses would be tested as they engage in activities that are considered 'dark' in the magic world. Some might even have a complete character transformation, going from good - natured mages to feared members of the dark guild.
The concept of Dark Natsu time travel is appealing because it allows for a fresh take on the Fairy Tail story. We get to see Natsu in a different light, his darker side, and how it affects the events he encounters during time travel. It also adds an element of mystery as we wonder how his actions will change the past or future.
I'm not sure who exactly Natsu is just from 'natsu reads fanfiction'. It could be a normal person who just enjoys reading fan - made stories. Maybe it's a nickname for someone within a particular fan community.