If in the fanfiction Natsu reveals his dark past, it might change how readers/viewers see his relationships. For example, they may understand his protectiveness over certain characters better as it could be related to his past experiences. Also, it could make his character more relatable as many people have their own dark pasts to deal with.
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.
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.
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.
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.
The fanfiction can create new plotlines. If it reveals something unexpected about Natsu's past, like a connection to a dark magic or a hidden enemy, it could lead to new adventures and conflicts within the Fairy Tail universe. It might also change the way other characters view Natsu, leading to different interactions.
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.
If Natsu is a girl in this fanfiction, her character might change in terms of her relationships. For instance, she may be more self - conscious about her appearance compared to when she was male. Also, her interactions with male characters like Gray could shift. Instead of their typical rival - like banter, there could be a more complex emotional undertone, like a friendly - rivalry with a hint of romantic tension perhaps.
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.