Well, it could be about Naruto attaining a position of an eternal emperor. Maybe it involves him ruling over the ninja world in a new and unique way, with new powers and responsibilities.
Since it's a Naruto fanfic, 'eternal guardians' might be a new element added to the existing Naruto lore. It could be about how these guardians are connected to the different ninja clans. For example, they might have a special bond with the Uchiha clan because of their sharingan powers or with the Uzumaki clan due to their strong life force. The fanfic may also focus on the training or battles that the main characters have with these eternal guardians to gain new powers or to protect the world from a new threat.
I'm not sure specifically as there could be many different 'Naruto Eternal Darkness' fanfics. It might be a fan - created story that delves into darker themes in the Naruto universe, perhaps exploring the characters in more complex and often shadowy situations, like a new villain arising that brings eternal darkness to the ninja world or a character's fall into a very dark path.
It could be about Naruto achieving a status of an eternal king in some sort of alternate universe or fan - created storyline. Maybe it shows Naruto ruling over Konoha or the entire ninja world for an eternity, with new challenges and adventures related to maintaining his eternal reign.
The 'naruto eternal sharingan fanfic' could center around the origin of the Eternal Sharingan in a unique fan - created story. It could explore the relationship between the character with the Eternal Sharingan and other characters in the Naruto world. For example, how their power affects their friendships or rivalries. It may also involve the character unlocking new abilities with the Eternal Sharingan that are not shown in the original series.
Since it's related to Naruto, Naruto himself is most likely a main character. He is the one becoming the eternal emperor.
I'm not sure specifically as there could be many different interpretations in such a fanfic. It might involve Naruto in an imperial - like role, perhaps ruling a kingdom or having a lot of power and influence in a made - up imperial setting.
In the fanfic, Naruto having the Eternal Mangekyou Sharingan could lead to a change in his relationships. His friends might be both in awe and a bit worried about this new power he has. Sasuke, being an Uchiha, could have a complex reaction. Maybe they would train together to better understand and control this power. Naruto could also use it to try and bridge the gap between the Uchiha and the rest of the village even more, as he now has a part of the Uchiha heritage in a very powerful way.
One possible plot could be that Naruto gains the Eternal Mangekyou Sharingan through some sort of unexpected and mysterious event. Maybe it's a result of a powerful jutsu gone wrong that fuses his own chakra system with that of a Sharingan - user. This new power could initially be difficult for Naruto to control, leading to him having to isolate himself to figure it out. As he masters it, he could use it in unique ways, like combining the Sharingan's abilities with his own Rasengan techniques, creating entirely new and powerful attacks.
The plot could involve some sort of time - travel or alternate dimension scenario. Naruto could be sent to a parallel world where the Uchiha clan was never massacred. There, he befriends the Uchiha and learns their ways. Eventually, he earns the right to receive the Eternal Mangekyou Sharingan through his deeds and his strong bond with the clan. With this new power, he has to find a way to return to his own world and use it to protect his friends and village from a new, greater threat.
I'm not entirely sure specifically what '123 eternal fire fanfic' is about without more context. It could potentially be a fan - created fictional story related to something called 'eternal fire', but the '123' part is rather unclear. It might be a code, a sequence number within a series of fanfics, or just something added randomly by the creator.