After Natsu gets angry, the plot might develop with other guild members trying to mediate. Happy might try to calm Natsu down while Gray could be in the middle trying to make both sides see reason. This could create a lot of comical and tense moments in the fanfiction.
One possible reason could be that Erza might have taken on a dangerous mission alone without informing Natsu. Natsu is protective of his friends and would get angry if he thought Erza was putting herself in unnecessary danger.
When Natsu gets angry in 'Fairy Tail' fanfiction, he often becomes a force to be reckoned with. His magic power can flare up uncontrollably. For example, he might accidentally set things on fire around him as his Fire Dragon Slayer magic responds to his emotions. Enemies are likely to face his full wrath, and he may charge into battle without much thought for strategy, relying solely on his brute strength and anger-fueled magic.
When Natsu gets angry in the fanfiction, different characters have different reactions. Erza, being the strong and authoritative figure in the guild, would likely try to discipline Natsu in some way, but also understand that his anger often comes from a place of protecting his friends. Wendy would be a bit more timid in her approach. She might use her healing magic to try and calm Natsu's emotions, as she can sense the turmoil in his magic energy. And Makarov, the guild master, would probably give Natsu a stern look and a lecture about controlling his temper.
Natsu was looking forward to a delicious meal at the guild. But when he found out that someone had eaten all of his favorite food, his anger flared up. 'Who did it?' he growled, his eyes darting around the guild hall. No one answered, which only made him angrier. His nostrils flared as he stomped around, demanding answers. Erza tried to calm him down, but Natsu was beyond reason at this point. 'I'll find out who it was and they'll pay!' he shouted, his voice echoing through the hall. His hair seemed to stand on end as his anger reached new heights.
He could marry an original character created specifically for the fanfiction. This character could be a powerful mage from a far - off place who crosses paths with Natsu during one of his adventures.
One of the senior and more experienced members of the guild. They have seen a lot and know how things should be done in the guild. If Natsu acts in a way that goes against their long - established ways, they would not hesitate to berate him.
In a fanfiction, Natsu might get angry if he was wrongly accused of something. Say, if he was blamed for a crime he didn't commit in the guild or in the magical world at large. He's an honest person, and being falsely accused would be a huge blow to his pride. Another possible reason is if a magic - based experiment went wrong because of someone else's carelessness and it put his friends in danger. Natsu values the safety of his comrades, and such a situation would make his blood boil. Also, if someone were to try and break up the Fairy Tail guild by causing internal disputes, Natsu would be enraged as he loves the unity and spirit of the guild.
It could be Gray. Although they are friends most of the time, in a fanfiction, there could be a plot twist where Gray's envy of Natsu's abilities gets the better of him, and he betrays Natsu. Maybe Gray thinks that by getting rid of Natsu, he can be the top mage in their guild.