Friendship is a big theme too. Characters from different universes in Sailor Moon crossover fanfic often become friends and learn from each other. They support each other in battles and in personal growth. Also, the theme of saving multiple universes is quite common. Since it's a crossover, there are usually threats that endanger both the Sailor Moon universe and the other crossed - over universe.
Another fanfic concept is that there's a threat in Gotham that has a connection to the Moon Kingdom's past. Sailor Moon travels to Gotham to investigate. There, she meets Batman, who is initially skeptical of her magical powers. But as they start to work together, they realize that their skills are complementary. For example, Sailor Moon's ability to heal could be useful for Batman's injured allies, and Batman's detective skills could help Sailor Moon figure out the mystery behind the new threat.
One idea could be a story where Goku and Sailor Moon team up to fight a common enemy. Maybe a powerful demon that is threatening both their worlds. They could learn from each other's fighting styles, like Goku showing Sailor Moon how to better use her physical strength and Sailor Moon teaching Goku about the power of friendship and love in combat.
One idea could be that Ranma accidentally stumbles into the world of Sailor Moon. Maybe he gets caught up in a fight against a youma and the Sailor Scouts mistake him for an enemy at first. But then they realize he has his own unique fighting skills and they team up to defeat the common foe.
Another interesting concept is a love triangle. Suppose Ranma falls for Sailor Moon, but Tuxedo Mask is already in the picture. This could lead to a lot of comical and tense situations. Ranma might try to outdo Tuxedo Mask in protecting Sailor Moon, leading to some friendly rivalry. Also, his curse could add an extra layer of complication. What if he turns into a girl when he's around Sailor Moon at an inconvenient time?
Another great one is 'Sailor Moon x Naruto: The Shinobi Senshi'. Here, the Sailor Scouts are transported to the Naruto universe. The Scouts have to adapt to the ninja world while also sharing their own powers and knowledge. The story delves into how the two groups can work together, with Naruto and his friends being intrigued by the Scouts' abilities and the Scouts learning about chakra and ninja techniques.
Well, one possible plot could be that the Sailor Scouts end up in the world of Diabolik Lovers. Maybe Sailor Moon's pure heart catches the attention of the vampire brothers. They might initially see her as prey but then become intrigued by her powers and the fact that she doesn't cower easily. The Scouts would then have to deal with the vampires' dark nature while also trying to find a way back to their own world.
Power is a big theme. The powers of the Sailor Scouts, which are based on elements like the moon and stars, are different from the vampiric powers in Vampire Knight. In crossover fics, there's often a comparison or a combination of these powers. Also, the idea of good vs evil is common. Sailor Moon and her friends are the defenders of love and justice, while vampires in Vampire Knight are often seen as more morally ambiguous. So seeing how they interact in the face of threats is a theme. Sometimes, there's also the theme of transformation. Both series have elements of transformation, and in crossovers, it can be interesting to see how the two types of transformations interact.
It's possible. Since Sailor Moon fanfics can range from being very close to the original anime's style to completely re - imagining the story, coffee could fit in either way. If the fanfic is set in a more contemporary or alternative universe, coffee would be a very normal addition. It could be a plot device too, like a poisoned coffee or a coffee that gives special powers in a magical coffee shop within the Sailor Moon world.
In a crossover, the characters might interact through a shared mission. Let's say there's a powerful villain that is causing chaos in both the Ranma and Sailor Moon universes. Ranma and the Sailor Scouts would have to put aside their differences and work together. Akane from Ranma's world could be jealous of Ranma's closeness to Sailor Moon, which would create some drama. Meanwhile, Sailor Mars might be suspicious of Ranma at first, thinking he could be a new enemy, but as they work together, she realizes he's an ally. This would lead to a development of their relationships.