In general, when looking for such a specific fanfiction, it's important to be patient. Since it's a rather specific combination of elements from Fairy Tail, it may not be as common. You could also try reaching out to other Fairy Tail fans you know. Maybe they've come across something similar or could even be inspired to write one if it doesn't exist yet.
I'm not sure there are a lot of very specific fanfictions just named 'firye tail natsu eyes of sun god'. But you could start by checking out big fanfiction platforms like Fanfiction.net or Archive of Our Own. Try using those exact words in the search bar to see if any relevant stories pop up.
Maybe the 'eyes of the sun god' are a key to an ancient mystery in the Fairy Tail world. Natsu, with his newfound eyes, embarks on a journey to uncover the truth. Along the way, he faces challenges that test his loyalty to his guild and his own strength. His friends in Fairy Tail might be initially skeptical or worried about this new development in Natsu, but they gradually come to support him as they see the potential of the 'eyes of the sun god' powers.
Well, the 'Eyes of the Sun God' in the 'Fairy Tail Hisui' fanfiction could symbolize a source of great energy. Maybe it has the power to control light or heat. It could be that characters are on a quest to either obtain it for its power or to keep it out of the wrong hands. It might also have some connection to the history and lore of the 'Fairy Tail' world in the Hisui part of the story.
One great 'Fairy Tail Natsu Dragon God Slayer' fanfiction is 'The Dragon's Ascent'. It really delves into Natsu's growth as a Dragon God Slayer in a unique way. The author creates new challenges for Natsu that are both exciting and in - line with the Fairy Tail universe.
Some characters might be protectors of the 'Eyes of the Sun God'. They could have a sworn duty to keep it safe from those who would misuse it.
I've read one where Natsu and Female Laxus compete in a guild - wide tournament. At first, it's all about winning for themselves. But as the tournament goes on, they start to understand that they are both representing Fairy Tail. They begin to work together in a way, like when they face an opponent who is using dirty tricks. They combine their powers to defeat the cheater and in the end, they both gain a new respect for each other and for the guild.
One great 'Fairy Tail Child Natsu' fanfiction is 'Natsu's Childhood Adventures'. It delves into Natsu's early days in Fairy Tail, showing his interactions with the other members as a child. It's full of heartwarming moments and also some exciting battles against small - time villains.
I really like 'Etherious Natsu's Adventure'. This fanfic takes Natsu on a journey where he has to face some of the darkest secrets of his past as an Etherious. It's well - written with a lot of action and emotional moments. For example, there's a part where Natsu confronts a figure from his forgotten past, and the way it's described is really engaging.
One great time travel fanfiction in the Fairy Tail universe could be 'Time's Twist'. In this story, Natsu and Wendy are sent back in time and have to figure out how to get back. It has really interesting character interactions, especially when they meet younger versions of their guild mates. They also have to deal with the threat that caused the time travel in the first place, which adds a lot of excitement to the plot.
Another interesting one is 'Gray and Natsu: Beyond the Guild'. This fanfic explores what would happen if Gray and Natsu left the Fairy Tail guild for a while. They end up in a strange land where they have to rely on each other to survive. It delves deep into their friendship and shows how they grow as individuals and as a team. The descriptions of the new land are really vivid and add to the overall charm of the story.
A really interesting fanfiction is 'Juvia, Natsu and the Lost Magic'. Here, Juvia and Natsu are on a quest to find a lost magic. Along the way, they encounter many challenges. Juvia's water - based magic and Natsu's fire magic create some really cool and unique battle scenes. The story also has a sub - plot about their friendship growing stronger, and how they come to rely on each other in ways they never expected.