One interesting fanfiction could be about a character from Naruto who somehow gets transported to the Fairy Tail universe and has to deal with the magic there while still having their EMS powers. For example, Sasuke could end up in Magnolia and form an unlikely alliance with Natsu to fight a common enemy.
Another concept is the character development. The presence of the Eternal Mangekyo Sharingan often brings a deeper level of conflict and growth for the characters. They might have to struggle with the power it bestows, such as the risk of going blind or the moral implications of using its more sinister abilities.
One interesting concept could be new and unique jutsu. For example, the author might create a jutsu that combines the powers of the eternal mangekyo in a way that has never been seen in the original Naruto series. Another concept could be different character relationships. Maybe in the fanfiction, characters who were enemies in the original become allies, all because of the power of the eternal mangekyo.
Sasuke Uchiha is often a central character. Since he already has the Sharingan in the original series, in fanfiction with the Eternal Mangekyo Sharingan, he can be further developed. His journey to master this new level of power and how it affects his relationships, especially with Naruto, can be a major focus.
One possible plotline could be Naruto unlocking the Mangekyo Sharingan through some strange and unforeseen means, perhaps a powerful jutsu backfires and gives him this new power. Then he has to struggle with controlling it while his friends are both amazed and a bit worried about this new development in him.
The Sharingan in such a fanfiction could be used as a tool for a Fairy Tail character to gain an edge in their battles. They might initially struggle to control it, but as they learn more about it, they become a formidable force. For instance, they could use the Sharingan's genjutsu abilities to deceive opponents in the Fairy Tail battles.
A possible fanfiction could involve a Fairy Tail mage getting the Mangekyou Sharingan somehow. This could lead to them having to deal with the dark side of the Sharingan, like the loss of eyesight over time. At the same time, they could use the Sharingan's powers, such as predicting opponents' moves, to become a stronger mage in the Fairy Tail guild.
One interesting storyline could be Naruto using the Sharingan to copy the magic of Fairy Tail wizards. He could then combine his ninja skills with the copied magic, creating unique fighting styles. For example, he might copy Erza's requip magic and use it to quickly change his ninja tools during battle.
One common theme is power struggle. When a Harry Potter character gets the Eternal Mangekyo Sharingan, they have to deal with the new power and how it affects their relationships. Another theme is identity. They might question who they are now that they have this new ability from a different universe. For example, a Gryffindor might struggle with the more 'ninja - like' aspects of the Sharingan that seem at odds with the Gryffindor values.
The concept of destiny could also be a shared element. In Naruto, characters often have a pre - determined path related to their powers. In Fairy Tail, there are prophecies and destinies for some characters. In fanfiction, the EMS in the Fairy Tail setting could be part of a character's fated journey, like being the key to fulfilling a great prophecy in the Fairy Tail universe.
Well, I don't have a specific 'Harry Potter Eternal Mangekyo Sharingan' fanfiction to recommend right off the bat. But when you're looking, consider the reviews and ratings of the stories. A highly rated story is more likely to be well - written. In these fanfictions, you might expect to see things like a Harry Potter character training to master the Eternal Mangekyo Sharingan, perhaps with the help of a character who has knowledge of both the wizarding world and the Naruto universe. This could lead to some really interesting character development and plot twists as they navigate two very different power systems.