There could be a fanfiction where an STC holds the key to a new type of weapon. In the story, a Space Marine chapter teams up with Imperial Guard units to protect the STC from Chaos forces who want to use it for their evil purposes. The story could detail the intense battles and the sacrifices made to safeguard this precious technology.
A great fanfiction might revolve around an STC that has the ability to terraform a dead planet. A group of Adeptus Mechanicus explorers find it but have to deal with internal power struggles within their own ranks, as some want to use it for the glory of the Mechanicus, while others believe it should be shared with the Imperium as a whole. The story would explore themes of loyalty, power, and the future of the Imperium.
One interesting story could be about the rediscovery of an STC in a long - lost sector. It might involve a group of Tech - Priests on a quest to retrieve it and face various xenos threats along the way.
Space Marines can also be main characters. They might be tasked with protecting an STC site or escorting Tech - Priests to retrieve an STC. Their combat skills are crucial in fending off threats.
There might be a fanfiction where a group of Imperial Guardsmen encounter a Necron tomb world awakening. This story could explore the horror and confusion of the guardsmen as they face the ancient and powerful Necrons, and how they try to survive against overwhelming odds. It could also show the Necrons' view of the 'inferior' organic lifeforms.
There might be a fanfiction where a Primarch is reborn in a different era of the Warhammer 40k universe. In this story, they have to adapt to the new circumstances, which are very different from what they knew. They might find that the Imperium has changed in ways they can't fathom, and they have to fight new enemies and face new politics within the Imperium.
Some fanfictions might center around the battles between different Primarchs. For instance, the confrontation between Horus and Sanguinius. In these stories, the authors often delve into the tactical aspects of their warfare as well as the emotional turmoil of the Primarchs. Additionally, there are fanfictions that show the Primarchs interacting with normal Space Marines in unique ways, perhaps mentoring them or learning from them in some cases.
There are fanfictions that focus on the relationship between different Eldar Craftworlds. For example, a story where two Craftworlds must unite their forces against a sudden Tyranid invasion. This involves political intrigue as well as epic battles, with the Eldar using their psychic powers and advanced weaponry in creative ways.
There are often stories where an original character in the fanfiction is a tech - priest who discovers a long - lost technology. This discovery sets off a chain of events as different factions, such as the Imperium and the xenos races, all try to get their hands on this new - found tech. It's full of intrigue, battles, and moral dilemmas as the tech - priest tries to decide what to do with the technology.
One interesting story could be about a Space Marine who discovers the power of his Christian faith within the brutal and dark universe of Warhammer 40k. His faith gives him an extra edge in battle against the forces of chaos.
Some 'Warhammer 40k Tau' fanfiction might explore the Tau's attempts to convert other species to the Greater Good. This could involve diplomatic negotiations, battles, and moral dilemmas as they try to expand their ideology in a universe full of different beliefs and cultures.
One interesting fanfiction might be about Isha's role in the complex web of the Warhammer 40k universe. It could explore her relationships with other deities or her influence on certain races. For example, a story could focus on how she might secretly be guiding a group of Eldar through a difficult time, using her unique powers.
One interesting concept could be the evolution of the factions. For example, how the Space Marines might have developed new combat tactics or even new genetic enhancements. Another could be the exploration of new planets and the strange alien species that might be discovered. Also, the political intrigue within the Imperium could be a fascinating aspect, like the power struggles between different segments of the military or the Adeptus Terra.