He might initially be in disbelief. Natsu is used to the loyalty among his Fairy Tail comrades, so betrayal would be a shock to him.
Natsu could turn vengeful. Given his fiery nature, he would not take betrayal lightly. He'd want to make those who wronged him pay for their actions.
Natsu would likely be extremely hurt. He has always been loyal to Fairy Tail, so being betrayed would be a huge blow. He might initially be in disbelief, not wanting to accept that his friends and guildmates could turn on him.
He might initially be shocked and confused. Natsu has always been so loyal to Fairy Tail, so this would be a huge blow to him.
He might be really angry at first. Natsu is a passionate character, and being kicked out unjustly would make him furious. He could storm off vowing to prove his worth and show the guild they made a mistake.
Natsu would be heartbroken. Fairy Tail is like his family. He'd probably go on a solo journey to clear his name and prove his loyalty. Erza would be stoic but deeply hurt. She'd start an investigation within the guild, using her influence and intelligence to uncover the truth. She might also isolate herself a bit while she figures things out.
Natsu would probably be very angry at first. He loves Fairy Tail like a family, so being kicked out would feel like a huge betrayal. He might go on a rampage, shouting and arguing with the guild members who made the decision.
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 could also be deeply hurt. He values his friends highly in Fairy Tail. If betrayed, he might isolate himself, doubting his own judgment in trusting people. This could lead to a period of self - discovery where he tries to figure out how to trust again. For example, he might recall the times when his friends in Fairy Tail were truly there for him and use those memories to heal and grow stronger in the face of this betrayal.
The guild would likely be shocked at first. They consider Natsu as one of their own, so his attack would be completely unexpected. Some members might try to talk him down, like Lucy. She has a close bond with Natsu and would probably try to reason with him.
One possible reason could be a misunderstanding. Maybe the other members of Fairy Tail misinterpret Natsu's actions as something harmful to the guild when in fact he has good intentions. For example, if Natsu accidentally destroys a valuable guild property while fighting a powerful enemy in the city, the guild might see it as irresponsible behavior and turn against him.
At first, they might be in disbelief. The members of Fairy Tail see Natsu as a core part of the guild, so it would be hard for them to accept that he has betrayed them. They would probably try to talk to him and find out what's going on. Some members might be angry immediately, thinking that he has turned his back on their family. But others, like Lucy, might be more hesitant to believe it and would look for a way to resolve the situation without conflict.