The fanfiction could start with Natsu's grand return. His friends are overjoyed but soon realize he's different. He might be haunted by the memories of the war. Maybe he lost some dear friends during the war and is now more determined to protect the ones he still has. His return could also trigger some rivalries. There could be those who are jealous of the newfound respect he has earned from the war, or those who think he has become too powerful and might be a threat. This would create a lot of drama and new storylines in the fanfiction.
One possible plot could be that Natsu returns with newfound powers. He might use these powers to help rebuild the world after the war, and also to reunite with his friends. Maybe he has to face some remnants of the enemy forces that still lurk in the shadows.
Maybe Natsu comes back with new powers. He might have to face old enemies that have grown stronger in his absence. Also, his relationships with his friends could have changed, and he'd have to work on rebuilding those bonds.
Another possibility is that Ash returns with some sort of special mission or knowledge from the war. He might be on a quest to use this new - found knowledge to make changes in his homeland. He could face opposition from those who don't believe in his ideas or are afraid of the changes he wants to bring. This could lead to a story full of adventure and self - discovery.
Maybe it's an old enemy who survived the war and has grown stronger. They hold a grudge against Natsu and his friends and are now seeking revenge. For example, if there was an enemy that was thought to be defeated before the war but managed to survive and is now back with a vengeance.
Obviously, Natsu himself is the central character. His friends like Lucy, Gray, and Erza are likely to be involved. They would be the ones to welcome him back and also be part of his new adventures or challenges that come after his return.
Well, one possible plot twist could be that Natsu returns with a new, super - powerful form that no one expected. Maybe he has mastered a long - lost magic during his absence.
The plot could be that the dragon's return disrupts the current peace in Natsu's world. Maybe the dragon has some unfinished business with an old enemy, and now that he's back, he drags Natsu into it. Natsu, being loyal to his foster father, follows him into this new conflict. This could involve a lot of action - packed battles and some emotional moments as Natsu has to deal with the potential danger to his foster father.
One possible plot could be that Natsu discovers his new power as a war god slayer magic user. He then has to face a series of powerful enemies who are threatening the world. Along the way, he might meet new allies who also have unique magic abilities. As he battles these foes, he gradually masters his war god slayer magic and becomes a more powerful wizard.
He could return with a whole new set of allies. During the war, he might have met other powerful mages who decided to follow him back to Fairy Tail. These new allies could bring different types of magic and skills to the guild. Also, Natsu might come back with a different perspective on life. The horrors of war could make him more determined to protect peace in the world and in his guild, leading him to take on a more leadership - like role in Fairy Tail.
Well, one possibility could be that Naruto returns with new powers. Maybe he has some kind of connection to an ancient force during his time 'dead' and now he has to face new threats that emerged while he was gone. For example, a new evil organization could have risen, and his return gives hope to the Hidden Leaf Village again.