Definitely Sasuke should be included. He could have some interesting interactions with Inner Moka. Maybe he's initially suspicious of her vampire nature but later comes to respect her skills. Sakura could also be a great addition. She could bond with Inner Moka over their shared strength and determination. Kakashi would be another good choice. His calm and experienced demeanor could contrast well with Inner Moka's more impulsive nature.
Another character that would be interesting to include is Jiraiya. His pervy nature could lead to some hilarious situations when he first meets Inner Moka. He could also be a source of wisdom for Naruto in dealing with this new and strange situation involving Inner Moka. And from the Rosario + Vampire side, Mizore could be included. Her cold and aloof personality could be an interesting contrast to the warm - hearted Naruto characters.
Well, Hermione would be a great addition. She could use her intelligence to help Harry and Moka understand the different aspects of their two worlds. For example, she could research about yokai and find ways to use magic to help Moka control her vampire side better.
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.
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 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.
In such a fanfiction, their love might develop gradually. Naruto could introduce Inner Moka to his world of ninjas, and she could show him the secrets of her vampire realm. Their relationship would be full of challenges, like dealing with the differences between their two species and the reactions of their respective friends. But their love could overcome these difficulties as they learn more about each other.
Naruto might be initially confused by Inner Moka Lemon's powers and appearance. But his friendly nature would make him quickly try to befriend her. He could ask her a lot of questions about her world and abilities.
Obviously, Tsukune and Inner Moka are the main ones. Tsukune is the relatable human element. He's the one who has to adapt to the strange world of monsters. Inner Moka, on the other hand, is a key part of the supernatural side of the story. She has her own motives, desires and relationships within the monster community. And their relationship with each other is what often drives the stories in this fanfiction genre.
Vampire Naruto could start off as a loner due to his different nature, but as he teams up with Inner Moka, he could learn the value of friendship and cooperation. Inner Moka could develop her fighting skills further by learning some of Naruto's ninja techniques. They could both grow in terms of their emotional intelligence as they face different challenges together, like dealing with prejudice from their respective communities.
Inner Moka is also likely to be in these fanfictions. Her more aggressive and powerful side compared to outer Moka can create different scenarios. For example, she might be initially hostile to Naruto but then gradually warm up to him as she sees his good qualities.
Kurumu would be a great character to include. She has a crush on Tsukune and her jealousy towards Moka could add some interesting drama to the side story. Also, Mizore, with her cold exterior but warm heart towards Tsukune, could bring in some unique interactions. Gin, being a werewolf, could also be included as he has an uneasy relationship with the vampires, which could create tension and conflict in the side story.