Perhaps a plot where Kimimaro Otsutsuki has to form an alliance with a group of outcasts. They initially don't trust each other, but as they face common enemies, they learn to work together. Kimimaro could use his unique abilities to protect the group and in turn, they teach him some new skills.
One interesting plot idea could be Kimimaro Otsutsuki being sent on a secret mission to a far - off planet. He has to face various unknown enemies and strange terrains. Along the way, he discovers a new form of chakra that he has to master in order to complete his mission.
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.
One idea could be to cross Hagoromo Otsutsuki with a character from a different anime universe, like Goku from Dragon Ball. They could have a power - level comparison and then team up against a common enemy. Another plot could involve Hagoromo in a modern - day world crossover, where he has to adapt to new technology while still using his ancient powers.
One idea could be Indra Otsutsuki crossing over into a modern-day world. He could struggle to adapt to the new technology and social norms while still having his powerful ninja abilities. Maybe he meets a group of people who initially fear him but then come to understand his situation and help him navigate this strange new world.
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 important aspect is the setting. Since it's related to Kimimaro Otsutsuki, it should be in line with the Naruto - like world. You can describe the landscapes, the villages, and the different ninja clans. When writing about Kimimaro, stay true to his character. If he is known for his loyalty in the original series, don't make him act out of character in your fanfic. And make your OC bring something new to the story, whether it's a new jutsu or a different perspective on the ninja world.
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 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.
One idea could be an otsutsuki crossover with the Naruto universe. Imagine an otsutsuki character interacting with Naruto and his friends, perhaps teaching them some of their unique jutsu or having a power struggle. Another idea is an otsutsuki crossover with a different anime like One Piece. The otsutsuki's otherworldly powers could create chaos in the Grand Line.