Well, a great concept in such fanfiction could be the exploration of different values. Gilgamesh values strength and glory, while Sailor Moon values love and friendship. How these two sets of values interact and conflict in the story can be really engaging. For example, Gilgamesh might initially scoff at Sailor Moon's reliance on friendship, but as the story progresses, he might come to see the power in it. And the reverse could also be true for Sailor Moon, as she discovers the importance of individual strength like Gilgamesh possesses.
One interesting concept could be the clash of different power systems. Gilgamesh is from a more ancient, myth - based power set, while Sailor Moon has her own unique magical girl powers. Their meeting might lead to a struggle for dominance in terms of power or a cooperation to face a greater threat. Another concept could be the cultural exchange. Gilgamesh represents an ancient Mesopotamian culture, and Sailor Moon is a product of modern Japanese pop culture. Their interaction could bring about a unique blend of cultural elements in the fanfiction.
In Gilgamesh x Sailor Moon fanfiction, a cool concept might be the character development. Gilgamesh, being a very proud and powerful character, could learn humility from Sailor Moon's kind and selfless nature. Or Sailor Moon could become more assertive and powerful under Gilgamesh's influence. Also, the idea of them teaming up against a common enemy, like an evil force that is threatening both their worlds, would be really exciting.
In Dragon Ball and Sailor Moon fanfiction, one interesting concept is crossovers. For example, imagining how the powerful Saiyans from Dragon Ball would interact with the magical Sailor Scouts. Another concept could be alternate universes where the characters have different powers or relationships. It might also explore what would happen if a character from one series trained with a character from the other.
Well, in Dark Kingdom Sailor Moon fanfiction, a common concept is the idea of redemption for some of the Dark Kingdom characters. Maybe a character realizes the error of their ways and tries to help the Sailor Guardians. Also, there could be fanfictions that focus on the relationships between the characters in the Dark Kingdom, like the power dynamics between the different villains.
Some fanfictions focus on their friendship in a more in - depth way. Maybe there's a story where Sailor Mars is feeling really down and Sailor Moon is the only one who can cheer her up. It shows how their bond is not just about fighting together but also about being there for each other through the tough times, like when Sailor Mars misses her family or is having a hard time with her studies.
One interesting story could be about how the characters from Sao and Sailor Moon meet in a virtual world. They might have to team up to fight a new kind of digital enemy that is threatening both their worlds. The unique powers of the Sailor Scouts combined with the skills of the Sao players would make for an exciting plot.
One interesting concept could be a crossover of Gilgamesh's power and Naruto's world. Maybe Gilgamesh's vast array of treasures could be incorporated into the ninja battles in Naruto. For example, his powerful weapons could be used by Naruto characters, adding a new dimension to their combat capabilities.
Their relationship could be portrayed as a mentor - mentee one. Gilgamesh, with his vast knowledge and power, could guide Sailor Moon in becoming a more powerful fighter. He could teach her about the ancient ways of combat and magic that he knows. Sailor Moon, in turn, could show Gilgamesh the power of modern - day values like hope and love.
One idea could be that the OC is a new senshi from a far - off planet who arrives on Earth just as a new threat emerges. The Sailor Scouts are initially suspicious but soon realize they need all the help they can get.
One possible storyline could be a crossover where Naruto's world is threatened by a villain from the Sailor Moon universe. Luna could play a key role in guiding Naruto and his friends, perhaps using her knowledge of magic and the Sailor Guardians. Another idea is that Naruto somehow gains Sailor Moon - like powers and has to learn how to use them in his own world.
In Gilgamesh Highschool DxD fanfiction, there might be concepts like Gilgamesh forming alliances or rivalries with the devils, angels, and fallen angels in the Highschool DxD world. His vast treasures from his own story could also play a role, perhaps being used as bargaining chips or powerful weapons in the battles that often occur in the Highschool DxD setting.
One idea could be that Usagi, being the kind-hearted leader she is, gradually forms a harem of characters who are drawn to her pure heart and strong sense of justice. For example, the various Sailor Scouts could develop deeper feelings for her beyond just friendship, leading to a complex web of relationships.