A really cool plot for this fanfiction could be that the reborn character as a Greek god has memories of the modern world. They could introduce new concepts to the Greek world, like modern technology in a very basic form. Maybe they use their knowledge to create something unique that impresses the other gods. Also, they could use their modern - day values to change the way the gods interact with mortals, for instance, promoting more equality in the way they treat different mortals instead of just favoring the heroes.
One idea could be exploring the newfound powers. For example, if reborn as Zeus, dealing with the power to control lightning and ruling the gods. Another could be the relationships with other Greek gods. Maybe there are rivalries or alliances that were not expected. And also, the protagonist could try to change the fates of mortals, like preventing a great tragedy from happening in a mortal city.
Well, a plot could involve the main character being reborn as a minor Greek god and trying to gain more recognition among the pantheon. They might have to complete certain quests or challenges. Or perhaps the story could focus on the character's struggle to adapt to the Greek godly lifestyle which is so different from their previous human existence. This could include understanding the complex hierarchies and traditions of the gods.
Apollo is often a favorite. He's the god of music, poetry, and prophecy. Reborn as Apollo, the character could explore the world of art in the Greek setting and also use their prophetic powers in interesting ways. Also, Poseidon is popular. With his control over the seas, there are many nautical adventures and power struggles that can be written about.
One possible plot could be Naruto being the son of a Greek god in secret. He discovers his divine heritage during a mission in the Naruto world. With his newfound godly powers, he can control elements in a way no one else can, like summoning lightning bolts similar to Zeus or controlling water like Poseidon. This would completely change the power dynamics in the Naruto universe.
One idea could be a new vampire character being reborn in the Twilight universe with a special power, like the ability to control the weather. This would create a whole new dynamic as they interact with the Cullens and other vampires.
One idea could be a story where the protagonist discovers a hidden power within a seemingly weak Pokemon in the Reborn region. This power could be the key to saving the region from a new, mysterious threat.
One idea could be that the reborn character tries to prevent Obito's fall to the dark side. They could use their knowledge of the future to stop Madara from manipulating him. For example, they might intervene during the battle where Obito was thought to be dead and expose Madara's true intentions early on.
Well, a plot could be that the reborn character discovers a hidden power within Kryptonian abilities that no one else knew about. This could put them in a position where they are both feared and revered. Also, they could form an unlikely alliance with a group of Kryptonians who were considered outcasts. Together, they try to bring about a new era on Krypton. Another interesting plot would be the character being sent on a mission to a different planet. Since they are reborn as a Kryptonian, they have unique skills for this mission and face various challenges during it.
One idea could be that the reborn character has to deal with the Hulk's uncontrollable rage in a new way. Maybe they have some special ability from their rebirth that can calm the Hulk down. For example, they can communicate with the Hulk on a deeper level, like understanding his fears that fuel the rage. Another plot idea is that the reborn character uses the Hulk's strength to protect a world that is different from the original Hulk's universe. They might face new enemies and challenges that require both the Hulk's brute force and the character's unique knowledge from their past life.
One idea could be exploring Homelander's childhood from the perspective of the reborn character. Maybe the character tries to prevent Homelander from becoming the villain he is. Another plot could involve the reborn character using their knowledge of Homelander's weaknesses to try and control him for the greater good. And a third could be that the character is reborn as Homelander himself and has to deal with the internal struggle of his powers and his public image.
Maybe the reborn Saiyan has memories of their previous life and tries to use modern - day knowledge to change the fate of the Saiyans. For example, they could introduce new technologies or strategies for fighting that would give the Saiyans an edge. They might also try to prevent the destruction of Planet Vegeta by warning the Saiyans about Frieza's true intentions in a more convincing way than Vegeta did in the original story.
One idea could be that Harry is reborn with all his previous memories intact. He uses this knowledge to change the course of events much earlier. For example, he could start befriending Hermione and Ron in a different way, perhaps by being more upfront about his past experiences and the threats they will face.