Another concept could be the origin of the inner demons. In Naruto fanfiction, some might explore if the inner demons are a result of some ancient curse or a by - product of the chakra system. It can lead to really cool plot twists and character developments. Maybe a character discovers that their inner demon was actually put there by an enemy long ago to weaken their clan.
Often, these fanfictions develop characters through their relationships with their inner demons. A character might start to see their inner demon as a sort of mentor or a warning sign. For example, if a character is too greedy in the Naruto world, their inner demon could represent the extreme of that greed and the character has to learn to balance it. This kind of development can change the way the character approaches power and friendship.
A fanfiction could also be based on Inner Moka being curious about Naruto's world. She decides to visit it, with Naruto as her guide. Along the way, they face various challenges, like dealing with people who are afraid of Inner Moka's vampiric nature. Naruto has to use his skills to protect her and show his world that she means no harm.
Hinata is popular too. In the context of inner naruto fanfiction, it could be about Naruto finally realizing Hinata's true feelings for him on a deeper, more internal level. How Naruto's view of Hinata changes from just a shy classmate to someone he has a special connection with.
One idea could be a crossover where Naruto finds himself in the world of Inner Moka Lemon. He could team up with her to fight a common enemy that threatens both their worlds. Maybe an evil force that wants to steal Inner Moka Lemon's powers and use them to take over Naruto's world as well.
One common theme is self - discovery. Inner Sakura often represents Sakura's true self that she's hiding, and through interactions with Naruto, she starts to discover more about herself. For example, in some fanfictions, she realizes her true feelings for Naruto because of how Inner Sakura reacts to him.
One idea could be a story where Naruto, as a vampire, accidentally stumbles into the world of Inner Moka. He initially struggles to adapt to the new and somewhat strange rules there. For example, he has to deal with the different power dynamics among the characters in that world. As he and Inner Moka interact more, they start to realize that they have more in common than they thought, like their strong wills and determination to protect those they care about.
One interesting concept could be exploring Naruto's inner thoughts during his training with Jiraiya. Maybe how he really felt about leaving Konoha for such a long time and the pressure of becoming stronger.
Some fanfictions show Naruto's inner darkness by making him question his ninja way. When faced with difficult situations and moral dilemmas, he may start to wonder if his usual optimistic and forgiving attitude is really the right approach. This internal struggle can be a significant part of his darker side.
In Naruto fanfiction, Naruto's inner darkness can be shown in various ways. It might be related to his loneliness as a child, with the villagers' hatred towards him. This could lead to a darker side where he questions his purpose and value, and may even have thoughts of revenge at times.