There could be a young Sith apprentice as a main character. This character is eager to prove themselves within the tribe and gain more power. They might be involved in various adventures and challenges within the tribe's society, such as competing with other apprentices or going on dangerous missions for the tribe's elders.
Perhaps a plotline where the Lost Tribe of the Sith has to face a new threat from outside their territory. This could force them to form alliances they never thought possible or use their Sith powers in new and creative ways. For example, they might have to team up with some Jedi who also have an interest in the new threat. The interactions between the two opposing forces would be full of tension and moral dilemmas.
The Sith Lords themselves are main characters, of course.
One memorable OC Sith could be Darth Zyra. She has a very distinct look with her purple - hued lightsaber and her elaborate black and red robes. Her power lies in her ability to manipulate the minds of her enemies, which she uses to great effect during battles in the Clone Wars.
Anakin Skywalker is a main character. He is the one who undergoes the major transformation in the story, from Jedi to Sith. Obi - Wan Kenobi is also important. He is Anakin's mentor and later has to face him. Padmé Amidala is a key character too as Anakin's love interest.
The Grand Inquisitor is quite popular. He's a menacing figure in the Star Wars universe, and in fanfiction, he often takes on even more complex roles. Writers like to explore his past, his relationship with other Sith, and his motives.
Rey is the most prominent character as the fanfictions are often centered around her and the Sith. Luke Skywalker can be quite popular too. He can be a guiding figure for Rey, or in some fanfictions, he has a different view on the Sith and Rey's potential connection to them. Maul is also a favorite. His unique look and his own journey in the Star Wars lore make him an exciting addition to stories involving Rey and the Sith. Writers might have Maul's spirit or some remnant of his power interact with Rey as she delves into the world of the Sith.
The Sith OC is obviously a central character. Then there are often female Sith apprentices or acolytes in the harem. There might also be alien species with Sith - like abilities or those who are attracted to the power of the OC. Some fanfictions may include redeemed Jedi who have turned to the dark side and joined the OC's harem.
Darth Maul could be a great character. His unique appearance and his thirst for power would make him an interesting addition to a Sith harem. He could be the enforcer, using his double - bladed lightsaber to protect the group.
Darth Maul is a great character to include. As a Sith, his menacing presence and his unique fighting style would add a lot to a Sith Pureblood fanfiction. Another one could be Count Dooku. His sophisticated and devious nature would interact well with the Sith Purebloods. And of course, General Grievous. Even though he's not a Sith, his role in the Clone Wars and his connection to the Separatists could create interesting storylines when paired with Sith Pureblood characters.
The main character is, of course, the Sith Warrior. There are also likely Sith masters who play important roles in the story, guiding or manipulating the Sith Warrior. And there could be other Sith characters that the Warrior interacts with, either as friends or foes in their journey.