A plot for Gilgamesh Danmachi fanfiction might be that Gilgamesh discovers a hidden part of the dungeon that has a connection to his past. Maybe it contains ancient artifacts or secrets related to his origin. As he delves deeper, he has to team up with some of the local adventurers from Danmachi. They are initially skeptical of him but soon realize his power and knowledge are invaluable. Together, they face various challenges and traps, and Gilgamesh also has to deal with his own internal struggles as memories from his past start to resurface.
A plot could revolve around a magic item that is found in the dungeon. This item has the power to grant a wish, but only one. The harem members all have different desires, which causes a lot of tension. Some might want to use it for Bell's benefit, while others have more self - centered wishes. This would lead to a complex web of emotions and decisions within the harem.
Maybe an OC that is an artificial being created by a powerful wizard long ago. The OC wakes up in the present day of the Danmachi world and has to learn about the new society and dungeon while also dealing with the fact that they are different from everyone else. They could form unique relationships with the existing characters as they try to find their place.
One idea could be that the reincarnated character has knowledge of future events in the Danmachi world. For example, they know about certain monsters' weaknesses or hidden treasures. This could give them an edge as they navigate the dungeon. Another could be that they are reincarnated as a non - human race in the Danmachi world, like a spirit or a dwarf, and they have to deal with the different cultural and physical aspects of that race. A third idea is that the character reincarnates with a special ability that doesn't exist in the normal Danmachi world, like the power to control time on a small scale, which would completely change their adventures in the dungeon.
Maybe Gilgamesh gets involved in the power struggles within the DxD universe. He might see the different factions as beneath him but still decides to meddle for his own amusement. He could try to reshape the power structure according to his own ideals, which would lead to many interesting confrontations.
Gilgamesh can be portrayed as a powerful and haughty figure. He could walk around the world of Danmachi with an air of superiority, looking down on the 'lesser' adventurers. His flamboyant style and his love for grandeur can be emphasized, like always wearing the most elaborate and expensive armor.
One idea could be that Gilgamesh, with his vast power and arrogance, arrives in the RWBY world. He might initially see the Huntsmen and Huntresses as beneath him but then becomes intrigued by Ruby's unique silver - eyed power. Another could be a scenario where Gilgamesh allies with a villain in RWBY, like Cinder, and together they try to reshape Remnant according to their desires.
One idea could be that Percy and his friends encounter Gilgamesh during a quest in a strange new realm. Gilgamesh could be a powerful ally or a mysterious foe. Maybe they have to work together to defeat a common enemy that is threatening both the world of Percy Jackson and the ancient lands of Gilgamesh.
One plot idea could be Kid Gilgamesh crossing over into a modern - day world and having to adapt to modern technology while still maintaining his pride and power. Maybe he gets into battles with modern superheroes who underestimate him at first.
One plot idea could be Bell and Hestia going on a special quest together that is different from the regular ones in the Danmachi world. Maybe they have to find a lost artifact that has a connection to Hestia's past. Another could be Bell getting into trouble in the dungeon and Hestia having to use her unique powers to save him, which could lead to a deeper emotional bond between them.
One idea could be to have Gilgamesh as a powerful ancient being who awakens in the RWBY world. He could initially be seen as a threat but then form an unlikely alliance with the main characters. For example, he might offer his knowledge of ancient magic to help them fight against a new, powerful Grimm.