In a 'Naruto otsutsuki bloodline fanfiction', you could have a plot where the Otsutsuki bloodline is slowly corrupting a character. They start to have strange visions and gain uncontrollable powers. As they struggle to keep their sanity, they must find a way to either embrace or rid themselves of this bloodline before it's too late. The story could explore themes of identity and self - control.
One idea could be a story where a young ninja discovers they have a hidden Otsutsuki bloodline power that gives them the ability to control gravity. This power sets them apart from their peers and makes them a target for both those who want to use their power and those who fear it.
One idea could be a crossover where Naruto's Otsutsuki powers somehow connect with the supernatural elements in DxD. For example, his ability to absorb and use chakra could be related to the magic in DxD. Maybe he could use his Otsutsuki powers to enhance the abilities of the devils or angels he meets in the DxD world.
One idea could be a story where an Otsutsuki member infiltrates the Akatsuki. They could have their own secret motives that conflict with the Akatsuki's goals, like using the Akatsuki as a tool to gather more chakra for their own clan's needs. Another plot could be about a young Naruto being mentored by an Otsutsuki in secret, and how this affects his relationship with the Akatsuki later on. Maybe he tries to persuade them to change their ways using the knowledge he got from the Otsutsuki.
One interesting idea could be exploring the unique powers that the otsutsuki clan brings into the Naruto universe. For example, how their god - like abilities might change the power dynamics among the existing ninja clans. Another idea could be the relationships between Naruto and otsutsuki characters. Maybe Naruto has to learn from them to gain new skills for protecting his village.
Maybe a fanfiction where Kaguya is reborn in a different form and Naruto is the only one who can sense her true identity. They form an unlikely alliance to fight a new common enemy that threatens both the ninja world and the secrets Kaguya holds.
One idea could be an Otsutsuki OC who comes to Earth not for conquest but to study the unique life forms here. They could befriend some of the local ninjas and learn about the concept of friendship, which is alien to the Otsutsuki. This would lead to a series of adventures where they have to protect their new friends from other more hostile Otsutsuki members.
In a fanfiction, you could have a scenario where an enemy uses a dark form of Bakuton bloodline power. Naruto and his comrades must find a way to counter it. They seek out an old hermit who has some knowledge of the Bakuton bloodline's weaknesses. Along the way, they learn more about the bloodline's connection to other elemental powers in the Naruto world, and how it can be used for both destruction and creation.
One idea could be a story where a character with the Shikotsumyaku bloodline discovers a new and powerful bone - related ability that no one in their clan has ever had before. This could lead to them being both feared and respected within the Naruto universe.
One interesting plot idea could be a story where a new character discovers they have a hidden Kaguya bloodline ability that has been dormant for generations. They struggle to control it at first, causing chaos in their village. Another could be a time - travel fanfic where a character goes back to the era of Kaguya and tries to change the course of history regarding the bloodline. Maybe they want to prevent the spread of the more dangerous aspects of the bloodline.
One idea could be a character having a bloodline that combines Naruto's Uzumaki chakra with Sao's game - like abilities. For example, they could have the Uzumaki's massive chakra reserves which they use to power up unique Sao - style skills in combat, like super - fast sword strikes enhanced with chakra. Another plot idea is a story where the bloodline causes a rift between different factions. Some see it as a threat while others as a new hope for their world. This could lead to all kinds of political intrigue and battles.
One idea could be a story where members of the Organization 13 with different bloodlines form an uneasy alliance to take on a common enemy. Maybe a powerful rogue ninja who threatens the entire ninja world.