One idea could be an adventurer who discovers a hidden part of the dungeon that has a different set of rules. For example, instead of monsters attacking on sight, they have to solve puzzles to progress further. Another could be an adventurer who forms an unlikely alliance with a group of monsters in the dungeon to survive against a more powerful common enemy.
Well, you could have a plot where the adventurer has a special ability that allows them to communicate with the dungeon itself. Through this connection, they learn secrets about the dungeon's origin and purpose. They might then try to use this knowledge to either gain power or bring about some sort of change in the relationship between adventurers and the dungeon. Also, an adventurer could be stuck in a time - loop within the dungeon, reliving the same day over and over until they figure out how to break the loop by making different choices each time.
One way is through their experiences in the dungeon. For example, if an adventurer faces a near - death experience from a powerful monster, it could make them more cautious or more determined to get stronger. Another way is through interactions with other adventurers. They might learn new skills or ways of thinking from their comrades.
One idea could be a story where the protagonist, a Pokémon transformed into a human - like form in the Mystery Dungeon world, discovers a hidden power within themselves. For example, a Pikachu might find out it can control a new type of electricity that no one has seen before. This could lead to them being both feared and revered among the other Pokémon in the dungeon.
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.
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.
One idea could be that Pikachu wakes up in a strange part of the mystery dungeon with no memory of how it got there. It has to team up with other Pokemon it meets along the way, like a Charmander and a Squirtle, to figure out the mystery of the dungeon and also find a way to get back home.
One idea could be to create an original character (OC) who has a unique power that catches the attention of a goddess. For example, an OC with the ability to manipulate time on a small scale. The story could revolve around how this power affects the relationship between the OC and the goddess, and how they team up to face challenges in the danmachi world. Maybe they have to deal with a powerful monster that is immune to normal attacks, but the OC's time - manipulation power gives them an edge in battle.
One idea could be exploring the backstories of the characters more in - depth. For example, delving into how the weapons came to be in the dungeon. Another could be creating a new character that enters the dungeon and has a unique relationship with the existing characters.
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.