It could be Naruto himself. Imagine if Naruto was secretly a descendant of Sparda. He would already have his own powerful chakra and then add the powers from Sparda's bloodline. It would make him an even more formidable force in the ninja world.
Maybe a new character could be the main character. A young ninja who discovers their connection to Sparda. This character could start off as an outcast, but as they learn to control their Sparda - derived powers, they gain respect and become a key figure in the story, perhaps even befriending some of the well - known Naruto characters like Sasuke or Sakura.
The fanfiction might explore the concept of a Naruto character being a descendant of Sparda in many ways. For instance, the character could have a special form or transformation similar to Dante's devil trigger in the Devil May Cry series (since Sparda is from that). This form could give them enhanced strength, speed, and abilities. They could also face challenges related to their dual heritage, like being shunned by some in the Naruto world who fear the unknown powers. And the story could revolve around how they overcome these prejudices and prove themselves as a valuable asset to their comrades and the entire ninja community.
In some fanfictions, the connection between Naruto and Sparda might be created through some convoluted plot devices. Maybe a powerful being in the Naruto universe has a link to Sparda's world, and through some magic or special bloodline manipulation, Naruto ends up being related to Sparda's bloodline. However, it's mostly a creative and often far - fetched idea in the realm of fanfiction.
One possible power is enhanced speed. Sparda is known for his agility in combat, and Naruto as his descendant in fanfiction could inherit this. He would be able to move so fast that his opponents could barely keep up. Another power could be the ability to manipulate demonic energy in a way similar to how he manipulates chakra. This could give him new jutsu - like abilities, for example, creating energy blasts with demonic properties. He might also inherit Sparda's resistance to certain types of attacks, like magic or dark energy attacks that are common in the Devil May Cry universe.
Perhaps it could be an existing Naruto character like Naruto himself, but in an alternate universe where he has this Nero connection. This would change his character arc quite a bit as he has to deal with this new aspect of his identity. He might have to learn new skills or face different types of enemies due to his Nero descendant status.
It could be Naruto himself. Imagine if through some magical or mysterious event, Naruto was revealed to be a descendant of Hiei. His already strong will and determination could be enhanced by Hiei's traits, making him an even more formidable ninja.
It could be a new character created specifically for the fanfiction. Maybe a young ninja who discovers their relation to Hagoromo later in life.
It could be a new character who is introduced as the descendant. Maybe a young ninja who has always felt a bit different from the others in their village. They start to have strange dreams related to Alice and then begin to uncover their unique heritage.
It might be Naruto's long - lost relative. This would add an interesting twist as Naruto is already a very powerful and well - known character. His relative having Frieza - like powers would create a lot of drama and new storylines. For example, Naruto might have to help this relative control their powers or deal with the consequences of having such a unique heritage.
The main character could be an existing Naruto character who somehow discovers they have Sesshomaru's bloodline. For instance, Naruto himself could be the one. Imagine if during one of his adventures, he unlocks a hidden power within him that is related to Sesshomaru. This would completely change his dynamic and how he approaches battles and relationships in the ninja world. He would have to learn to control new powers like Sesshomaru's poison claws or something similar.
Obviously Naruto would be one of the main characters. Since it's about his reincarnation related to Sparda. But there might also be characters from the Naruto series like Sasuke, Kakashi etc. who would be involved in the story. And depending on how the Sparda aspect is incorporated, there could be some new characters related to Sparda's world as well.