One possible reason could be a past trauma. Maybe he witnessed something really horrible during a battle or an incident at school that shocked him so much he lost his ability to speak. For example, if he saw a friend in great danger and was powerless to help immediately, it could have had such a psychological impact on him.
He might use sign language. If there are other characters in the fanfiction who know sign language, they can act as interpreters for him. For example, Lucy could have learned sign language to be able to communicate with Natsu better.
Perhaps Natsu is seen as a bad boy because he's from a different background than most of the students at Fairy Tail School. He might come from a poorer part of town and has a rougher attitude. He could be constantly getting into fights with the rich kids who look down on him, and through these conflicts, he learns about friendship and acceptance.
One great 'Fairy Tail Natsu School' fanfiction is 'Natsu's School Days'. It's really engaging as it shows Natsu's clumsy attempts to fit into a regular school setting. The author does a wonderful job of keeping Natsu's fiery personality while also exploring how he deals with things like exams and making friends in a new environment.
One possible scenario could be that the new kid is a huge fan of Natsu and joins Fairy Tail School Academy hoping to meet him. The new kid might be really nervous at first, but then Natsu's warm and friendly personality makes him feel welcome. Natsu could show the new kid around the school, introducing him to all the cool magical things there.
Yes, in a lot of Fairy Tail fanfiction, Natsu can be overpowered. Writers often like to amp up his powers for more exciting storylines. For example, they might give him new fire - based abilities or make his existing ones even stronger to defeat more powerful foes.
In fanfiction, Natsu's age can vary greatly. Some authors might keep him at his canonical age from the original Fairy Tail series, which is around 17 - 18 years old at the start. However, in alternate universe fanfictions, he could be older or younger depending on the plot. For example, in a time - travel based fanfic, he could be much older if the story takes place far into the future or much younger if it goes back to his childhood days.
I'm not sure exactly as it's a fanfiction. But it might be about Natsu in a high school setting in the Fairy Tail universe, being a badass, which could involve him getting into cool adventures, showing off his powers, and having some sort of unique relationships with other characters from Fairy Tail in this high - school - themed scenario.
Another plot could revolve around Natsu being the new kid at school and having to earn the respect of his classmates. He gets into various battles and challenges, not just physical ones but also magical duels of wits. His friends from Fairy Tail might visit the school from time to time to help him out or just to see how he's doing. And as he overcomes these challenges one by one, he gradually becomes a respected and feared figure at the school, all while still maintaining his fun - loving and loyal nature.
Maybe Natsu is seen as a bad boy because he challenges the traditional rules of the academy. He might believe that some of the rules are holding students back from truly exploring their magic potential. So he forms a sort of rebel group within the school, and they go on adventures outside the permitted areas to discover new types of magic. This could create a lot of conflict with the school authorities.