One idea could be that the Skeksis from 'The Dark Crystal' discover the power of the Force in the 'Star Wars' universe. They might try to capture Jedi to learn their secrets and use the Force for their own dark purposes, like extending their lives even further.
Imagine if a Sith Lord got hold of a shard of the Dark Crystal. He could try to corrupt it with the dark side of the Force, creating a new kind of dark power source. This could draw the attention of both the Jedi and the Skeksis, who would either want to destroy it or claim it for themselves. The fanfiction could then follow the battles and power struggles that ensue.
Perhaps a group of Gelflings end up on a Star Wars planet. They form an alliance with the Rebels. The Gelflings' unique abilities, like their connection to nature in 'The Dark Crystal', could be used to help the Rebels in their fight against the Empire. For example, they could use their skills to navigate through difficult terrains on a forest - covered planet that the Empire is trying to control.
Imagine a scene where a Gelfling meets a young Padawan. The Gelfling could show the Padawan their connection to nature and their own kind of magic, which might be different from the Force but still inspiring. On the other hand, if a Skeksis were to encounter a Sith Lord, there would be a power struggle for sure. Both are power - hungry and would likely try to outwit the other to gain more control over whatever they desire.
One idea could be exploring the life of a new Jedi who emerges during the Dark Empire era. They could start as a hidden Force - sensitive on a remote planet and then get drawn into the conflict between the remnants of the Empire and the New Republic. Another plot could focus on the dark side artifacts that are being unearthed during this time and how different factions are trying to control them. Or perhaps a story about a group of smugglers who accidentally get caught in the middle of the power struggle between the Empire and the Republic and have to use their wits to survive.
One idea could be exploring the backstory of a new, powerful Sith Lord in the Dark Destiny universe. Maybe this Sith Lord was once a Jedi apprentice who fell to the dark side due to a great betrayal. Another could be focusing on a group of rebels trying to find a long - lost Jedi holocron that holds the key to defeating the dark side once and for all in this fanfiction setting. A third idea might be a story about a young Force - sensitive character who is caught between the light and dark side, being courted by both the Jedi and the Sith.
A Dark Crystal and Star Wars crossover fanfiction could be really interesting. Maybe the unique creatures from The Dark Crystal could be found in a far - flung Star Wars planet. For example, the Skeksis could be some sort of dark force - using villains in the Star Wars universe. The Gelflings might be like a new species that the Jedi or the Sith take an interest in.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions from various fandoms, including ones that combine 'The Dark Crystal' and 'Star Wars'. Another option is FanFiction.net. Just search for the relevant tags like 'Dark Crystal' and 'Star Wars' on these platforms.
One idea could be Rey being lured to the dark side by a powerful Sith artifact. Maybe she discovers an ancient Sith holocron that shows her a version of the galaxy where the dark side rules supreme and she starts to believe that it's the only way to bring true order. Another plot could involve Rey being manipulated by a dark side user who preys on her insecurities about her past and her power.
Perhaps there could be a story where Naruto's chakra is seen as a unique form of energy in the Star Wars universe. The Sith see it as a means to enhance their dark side powers. They manipulate Naruto, showing him false visions of his past failures in Konoha, which makes him angry and more susceptible to the allure of the dark side.
One idea could be exploring the backstory of a minor Gelfling character. Maybe they have a secret connection to the Skeksis that they're trying to hide. Another could be a story about Gelflings from different clans coming together to form an even stronger resistance before the events of the show. And a third could be a fanfiction where a Gelfling discovers a new power within themselves that could potentially turn the tide against the Skeksis.
Since 'Dark a Star Wars Story' is not a familiar Star Wars entity, if it were to exist, it might tell a story set in the shadowy parts of the Star Wars galaxy. It could involve the Sith and their schemes. For example, it could show how the Sith manipulate events from the background, like how Palpatine manipulated the Clone Wars. It might also focus on the lives of those who are caught in the crossfire between the light and dark sides of the Force, perhaps a smuggler or a bounty hunter who has to deal with the consequences of the Sith's actions.
In a fanfiction, Ezra could be exposed to a dark side cult. They convince him that the Dark Side offers a more efficient way to bring order to the galaxy. He then starts to use dark side techniques in his fighting and decision - making. His fall to the Dark Side could be a long and tragic process, with him losing his moral compass along the way.