Lucy would be completely devastated. She and Natsu have a very close bond. She might go into a deep depression, constantly blaming herself for not being able to save him. Gray would be angry at first, feeling like he should have been there to help Natsu. Then he'd be sad and would probably vow to avenge Natsu. Erza would be strong on the outside but inside she'd be broken. She might try to keep Fairy Tail together in Natsu's memory. Happy would be inconsolable, constantly flying around looking for Natsu and refusing to believe he's really gone.
The other members of Fairy Tail would be in shock. Wendy would try to use her healing magic, even though she knows it's too late. She'd cry and feel like she let Natsu down. Gajeel would respect Natsu's sacrifice if it was for a noble cause but still be sad. He might say some gruff words about how Natsu was a worthy opponent. Makarov would be heartbroken as he saw Natsu as one of the guild's most important members. He'd probably hold a big memorial service for Natsu. And the rest of the guild would be in a state of mourning, with the whole atmosphere of Fairy Tail becoming very somber.
Gray would be shocked at first. He and Natsu have a long - standing rivalry - but also a deep friendship. He might initially be angry that Natsu would just leave like that, but then he would realize how much he'll miss him. He might also feel a sense of loss for the guild as a whole, since Natsu is such an important part of it.
Gray would be angry and sad at the same time. He was Natsu's rival but also his friend. He might lash out at first, blaming the situation or other people. But then he would turn his anger into a determination to find out what really happened to Natsu and seek justice if there was foul play involved. And he would also be there for Lucy and the other guild members, trying to keep them strong.
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.
Well, a common scenario is that Natsu dies in a battle against an ancient and powerful demon. He fights bravely but the demon's power is overwhelming. Natsu realizes that the only way to stop the demon from destroying the world is to use a self - destruct type of magic move. He does it, sacrificing himself for the greater good. Another could be that Natsu is tricked by a dark wizard into a magic - trapping spell. His friends try their best to break the spell but it drains Natsu's life energy until he dies. And there's also the possibility that Natsu's overuse of his dragon - slayer magic due to a series of intense battles causes his body to give out and he passes away.
Well, in these fanfictions, a frequent theme is the power of love. Natsu's love for Fairy Tail is so strong that he is willing to give his life. This can also lead to themes of inspiration for the other guild members. His death might inspire them to become stronger or to uphold the values he fought for. Additionally, there can be themes of afterlife or resurrection speculations, as fans might be interested in whether Natsu could come back in some way, which adds an element of hope to the otherwise tragic scenario.
Well, the plot could involve Natsu being the sole survivor of a great catastrophe that wipes out the rest of Fairy Tail. He might then embark on a journey to revive the guild. He could search for lost magic or artifacts that could bring his friends back. Maybe he'd face off against new and powerful enemies who were responsible for the destruction in the first place.
Lucy would be extremely distraught. She and Natsu have a very close bond. She might cry for days and even isolate herself from the rest of the guild at first. Gray would be angry and feel a strong sense of loss. He'd probably blame himself for not being there to help. Erza would be stoic on the outside but inside, she'd be deeply affected. She'd take charge of the situation, making sure Natsu's death was not in vain and that the guild stays strong.
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.
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.
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.