There are fanfictions that focus on the relationships within the Sisters of Battle. For example, a story could explore the bond between a novice Sister and her mentor. The novice might struggle with her faith at first, but through her mentor's guidance and shared experiences in battle, she grows stronger in her beliefs and combat abilities.
One interesting 'Warhammer 40k Sisters of Battle' fanfiction could be about a Sister of Battle's journey to redeem a lost world. In this story, she might face numerous heretical cults and have to use her faith and combat skills to overcome them.
Another great fanfiction idea could be a Sisters of Battle squad being sent on a secret mission behind enemy lines. They have to rely on their stealth, guile, and of course, their unwavering faith in the Emperor. Along the way, they encounter strange alien species and have to figure out how to deal with them while still achieving their mission objective.
Celestine is often a very popular character in fanfiction. Her divine nature and incredible combat abilities make her a fascinating subject. Writers can explore her connection to the Emperor's will in more depth.
I'm not really into lemon fanfics as they often go against the official tone of the Warhammer 40K universe. However, you can try searching on some fanfic websites like Archive of Our Own. Just be aware that such content might not be in line with the more serious and dark nature of the Sisters of Battle lore.
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.
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.
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.