It could be about Natsu finally opening up about a tragic event from his childhood that shaped his personality. Maybe it involves the loss of a loved one, or an experience that made him distrust a certain group of people.
In the 'natsu reveale his dark past fanfiction', it might be that Natsu discloses a past where he was part of a group that was involved in some unethical activities. However, he had a change of heart and left the group. But this past still haunts him as he fears that his former associates might come back to cause trouble for him or his current friends. This revelation could add a whole new layer of complexity to his character and his relationships in the fan - created story.
It could make him seem more vulnerable. Usually, he might come across as strong and fearless, but revealing his dark past shows he has his own insecurities and traumas.
His friends could be involved. For example, Lucy might stumble upon some old records or meet someone who knew Natsu in the past. Gray could also be part of it, especially if it has something to do with the magic world's secrets that they both are a part of.
It could be someone from Natsu's past. Maybe an old rival who knows about his dark secrets and wants to use them against him.
The 'natsu dark past secret fanfiction' might revolve around Natsu's family. There could be some dark secrets about his family that he has just discovered. Maybe his family was involved in some sort of dark magic or a feud with another powerful group, and Natsu is now starting to uncover the truth about it.
Well, it could be things like a tragic family history. Maybe Natsu's family was involved in some sort of dark magic that got them in trouble. Another possibility is that Natsu had a past encounter with a powerful and evil entity that left a mark on his psyche.
It could also be that Sakura has a dark past in the context of a magical or supernatural world. She might have accidentally unleashed a dark force in the past and has been trying to atone for it ever since. This could involve her having to face dangerous creatures or deal with powerful magic that has a corrupting influence.
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.
Another idea for this fanfiction could be that they were both students at a very old and secret magic academy in the past. Zeref was an outcast because of her dark magic, but Natsu didn't care. He befriended her, and together they explored the secrets of the academy and the magic within it. However, their friendship was soon tested when the academy's elders discovered Zeref's true nature.
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.
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.