Perhaps in the fanfiction, Voldemort's reincarnation is born into a more humble family and through his new life experiences, he starts to question his past actions. Harry, on the other hand, is intrigued by this new Voldemort and they embark on a journey of self - discovery together, exploring the gray areas between good and evil.
One idea could be that Harry starts having strange dreams where he sees through Voldemort's eyes. This could lead to him unknowingly helping Voldemort in some small ways at first, like revealing the location of some minor Order of the Phoenix safe houses. Another plot could involve the other characters slowly realizing something is wrong with Harry. For example, Hermione might notice that Harry is using some Dark Magic spells without hesitation, which is completely out of character for him.
A plot could involve a magical creature that bonds Harry and Voldemort in an unexpected way. For example, a rare faerie that makes them see each other's memories. Through this, Harry discovers some long - hidden secrets about Voldemort's past that could potentially change the course of their enmity. They then have to decide what to do with this new - found knowledge.
Maybe Harry discovers that Voldemort has a hidden motive for taking him as an apprentice. It could be that Voldemort believes Harry has a power that can be harnessed for a greater, more complex plan that involves not just ruling the wizarding world but changing the very fabric of magic itself. Harry then has to figure out how to either use this to his advantage or stop Voldemort from achieving his goal.
One idea could be a fanfiction where Voldemort has a change of heart due to some ancient magic. Maybe he discovers a spell that shows him the true consequences of his actions and decides to work with Harry to fix the wizarding world instead of destroying it.
One idea could be that Harry, influenced by dark magic, forms an uneasy alliance with Voldemort. They could team up to take over the wizarding world in a different way than Voldemort originally planned, perhaps by ruling jointly. Another plot could involve Harry exploring the darker aspects of his own magic and using some of Voldemort's knowledge to do so, which causes a rift between him and his friends.
One idea could be a fanfiction where Voldemort gets a second chance at life but without his dark magic powers. He has to learn to live as a normal wizard in the wizarding world and Harry Potter has to decide whether to trust him or not.
In this fanfiction, an exciting plot could be Naruto's encounter with the Dark Arts. Given his strong will and positive nature, he might have a unique way of combating dark wizards. He could use his sage mode to sense the presence of dark magic and his Rasengan could be transformed into a powerful anti - dark magic spell. His relationships with the characters from Naruto could also be mirrored in the Harry Potter world. For instance, he might see Ron as similar to Shikamaru, in terms of being a laid - back but reliable friend, and Hermione as a bit like Sakura, smart and strong - willed.
Well, perhaps Sasuke's reincarnation is sought after by Voldemort. Voldemort hears rumors of a powerful being with strange and unknown powers (Sasuke's Sharingan and ninja skills). So he tries to either recruit or eliminate Sasuke. Sasuke, on the other hand, is more interested in finding out the secrets of magic in this new world and how it relates to his own past powers. He might form an unlikely alliance with Harry Potter to resist Voldemort, as they both have unique powers that the Dark Lord fears.
Hermione is often a popular character. She might play a role in helping Harry understand the implications of Voldemort's reincarnation, using her vast knowledge of magic and history.
One idea could be a fanfiction where Voldemort is redeemed. Maybe after a near - death experience, he has a change of heart and tries to make amends for all the evil he has done. He could start by secretly helping Harry Potter against some other dark forces that emerge in the wizarding world.