Well, Archive of Our Own (AO3) is also a great place to find Kid Gilgamesh crossover fanfiction. Some crossovers might include him with modern - day settings or with characters from different mythologies. The tagging system on AO3 makes it easier to filter out exactly what you're looking for in terms of pairings and plot elements.
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.
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.
In the story, they start as sort of rivals. Gilgamesh is a powerful king who is a bit wild, and when Enkidu is created, he challenges Gilgamesh. But then they become friends. They share a deep bond that is tested through various trials. For example, when they face Humbaba, the demon of the cedar forest. Their relationship is complex and full of mutual respect in the end, and Enkidu's death deeply affects Gilgamesh.
The story of Gilgamesh is an ancient epic that follows the adventures and quests of the king Gilgamesh. It explores themes of friendship, mortality, and the search for meaning.
The Epic of Gilgamesh is not classified as a novel. It predates the concept of the novel and has different characteristics and structures. It's more like an epic poem or mythological tale.
He would likely be portrayed as arrogant. Given his status as a powerful and ancient figure in his original lore, in DxD fanfiction he would probably look down on most of the characters. He would act as if he is above the petty squabbles of the DxD world.