Well, a frequent theme is the clash of cultures. Harry comes from the wizarding world, but with his Otsutsuki side, there is often a struggle between the two different cultures. He has to figure out how to balance the magic he has known all his life with the strange and powerful abilities of the Otsutsuki. Also, friendship and loyalty are common themes. His friends in the wizarding world may not understand his new powers at first, but they still stand by him, and this is explored in many fanfictions. In addition, there are fanfictions that deal with the theme of prophecy. Harry's Otsutsuki blood may be linked to some ancient prophecies, and he has to fulfill his destiny as per these prophecies.
The theme of mystery is also common in Kaguya Otsutsuki fanfiction. Her character has a lot of mystery surrounding her, and fanfictions often try to solve these mysteries. For example, what was her life like before she came to the ninja world? And what secrets does she still hold? Writers use these questions to create engaging stories.
A common theme is power discovery. Sakura often discovers new powers related to the Otsutsuki in these fanfictions. For example, she might unlock some unique abilities that are connected to their ancient lore.
One possible plot could be that Naruto discovers he has some hidden Otsutsuki bloodline. This leads to him being ostracized by some in the village who fear his new - found power. He then has to go on a journey to learn about his Otsutsuki heritage, facing challenges along the way and also having to prove that he's still the same Naruto at heart.
One interesting otsutsuki fanfiction could be about an otsutsuki who decides to live among humans and tries to understand their emotions. This otsutsuki might start to form relationships with humans, which is a big change from their usual aloof nature.
One possible plot could be that Naruto discovers he has Otsutsuki blood in him. This could lead to him having new and uncontrollable powers that he has to learn to master. He might be shunned by some in Konoha who fear his newfound abilities, while others see it as an opportunity for Konoha to become even stronger. Naruto would then have to struggle with his identity and prove that he is still the same Naruto they know and love.
Some characters might be in awe of him. For example, his friends like Sakura and Kakashi could see him in a new light. They might be more cautious around him at first, not fully understanding the implications of his new bloodline. His enemies, on the other hand, would likely be more fearful or more determined to defeat him. The Hidden Leaf Village might also have a different attitude towards him. They could be both proud that one of their own has such a powerful bloodline, but also worried about the potential danger it could bring.
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.
Another common theme is crossovers and interactions. Writers like to create scenarios where characters from Naruto's Otsutsuki clan meet and interact with Bleach characters. This can lead to all sorts of interesting storylines, from team - ups to battles. For example, an Otsutsuki character might team up with a Bleach hero to fight a common enemy. It also allows for exploration of different cultures within the two universes. The ninja culture of Naruto and the spiritual culture of Bleach can clash or blend in interesting ways in these fanfictions.
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.