Maybe a powerful wizard who is jealous of the power of both the Shield Hero and the Dark Lord. He wants to eliminate them and take their powers for himself. He could be creating false rumors about the Dark Lord to keep the Shield Hero against him while he plots his own takeover.
One idea could be that the Dark Lord has a hidden past that is somehow related to the Shield Hero. Maybe they were once allies in a different realm before being corrupted. Another could be that the Dark Lord is actually trying to protect the world in his own twisted way and the Shield Hero has to figure out his true motives.
It could be another powerful dark wizard who sees the relationship between Sabrina and the Dark Lord as a threat to his own power and plans.
In many 'Harry Potter' fanfictions about 'Dark Lord Rising', it often explores the resurgence of Voldemort in new and creative ways. It might show different scenarios of how he regains power, like through dark magic artifacts that were not fully explored in the original books.
Well, a main character could be a former follower of the dark lord who has had a change of heart. They know the dark lord's weaknesses and plans from the inside. Also, a peasant girl who witnesses the early signs of the dark lord's rise and decides to take matters into her own hands. She could be a symbol of hope for the common people. And a wandering swordsman who has a code of honor and is drawn into the conflict against the dark lord by his sense of justice.
One idea could be exploring the backstory of the dark lord before his rise. Maybe he had a tragic past that led him to embrace the dark side. Another could be the perspective of those who oppose the dark lord's rise, their struggles and secret plans to stop him. A third idea is to create a new character who gets caught in the middle of the dark lord's rise and has to make difficult choices between siding with good or evil.
Power struggle is a common theme. It shows how the Dark Lord tries to gain more power and how the good side tries to stop him. There's also the theme of fear, as the wizarding community lives in dread of the Dark Lord's return.
It could be a powerful, ancient Titan who was banished long ago and has now returned for revenge. Maybe Kronos has an even more evil and powerful form that he takes on, becoming the Dark Lord. He wants to destroy the new order of the gods and demigods that has been established since his last defeat.
Perhaps it has an anti - hero as a main character. Someone who is initially drawn to the rising dark but then has a change of heart. Or it could be a group of characters, like a band of rebels in a dystopian - themed fanfic related to the 'rising of the dark' where they are fighting against an oppressive dark regime.
Yes, Rising of a Shield Hero is a manga.
Obviously, Naruto would be one of the main characters, just in his new 'dark lord' role. Sasuke could also be a major character, as his relationship with Naruto is so central in the original series. Their dynamic would likely be very different in this fanfiction, perhaps becoming more of an adversarial relationship.