Here's some plot ideas. A Sith Pureblood fanfic could center around a young Sith Pureblood who is sent on a mission to recruit new followers for the Sith cause during the Clone Wars. They encounter various species and have to use their wits and Sith powers to convince them. Maybe there's a Sith Pureblood who has a special connection to the dark side of the Force that allows them to see visions of the future. They use these visions to try and manipulate the outcome of key battles in the Clone Wars for the Sith's benefit. Also, a story about a Sith Pureblood who was once a Jedi captive and learned some Jedi teachings. They then try to incorporate these teachings into their Sith ideology, which causes chaos and confusion among the Sith and also makes them a target of both the Sith and the Jedi.
One plot idea could be a Sith Pureblood rising through the ranks in the Sith hierarchy during the Clone Wars. They might start as an apprentice and have to prove themselves by undertaking dangerous missions against the Jedi. For example, they could be tasked with infiltrating a Jedi stronghold to steal a valuable artifact. Another idea is a story about a Sith Pureblood who has a change of heart and tries to defect from the Sith. This would involve a lot of internal struggle as they fight against their dark side training and the fear of reprisal from the Sith Lords. A third plot could revolve around a group of Sith Purebloods who form a secret society within the Sith order, with their own goals and agendas that may or may not align with the overall Sith plans during the Clone Wars.
Another idea is that the Sith Empire decides to use a new form of Sith magic during the Clone Wars. This magic starts to corrupt the planets it is used on, and the Jedi have to find a way to stop it. The story could show the different reactions of various species to this new threat. For example, some might be more susceptible to the corruption while others are more resistant. The Jedi would have to form alliances with these different species to combat the Sith Empire's new weapon. This would involve a lot of political maneuvering as well as physical battles. It could also explore the nature of the Force and how the Sith's use of it in this new way affects the balance.
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.
A possible story idea could be that your OC Sith discovers an ancient Sith prophecy. They believe it will lead them to ultimate power. So, they start a quest to find the artifacts related to this prophecy during the Clone Wars. This could involve them infiltrating Jedi strongholds and causing chaos.
A great plot for Star Wars The Clone Wars fanfiction could be centered around a new, unknown planet that gets caught in the middle of the war. The planet has its own unique species and culture. The story could follow how the clone troopers and the Jedi interact with this new civilization, whether they try to protect it or use it for their own strategic advantages. Or perhaps a story where a group of clone troopers start to develop their own individual personalities and question their loyalty to the Republic due to some unethical orders they receive. This could lead to a conflict within the clone ranks and force the Jedi to take sides.
Well, a great storyline could involve an OC Sith who was once a Jedi padawan but was seduced by the dark side. In 'Star Wars The Clone Wars', this character could be on a journey to destroy their former Jedi friends while also dealing with the internal conflict of their new Sith identity. They may struggle with memories of their Jedi training and the relationships they had before turning to the dark side.
She could be a clone who rebels against the clone programming. Instead of blindly following orders, she starts to question the morality of the Clone Wars. She might try to find a way to end the war peacefully, even if it means going against her own side. This would create a lot of internal conflict as well as external conflict with her superiors and comrades.
A great plot idea would be to have a story centered around a group of younglings who are accidentally caught in the crossfire of a Clone Wars battle. They have to rely on their basic Jedi training and the help of some friendly clone troopers to survive. As they journey through the war - torn landscape, they grow and learn more about the reality of the war. Also, a story about a Separatist scientist who has a change of heart and tries to defect to the Republic with valuable information about new droid technology could be really interesting. He has to avoid being hunted down by his former allies while trying to make his way to the Republic lines.
One interesting plot idea could be exploring the backstory of the Ones on Mortis in more detail. Maybe a young Jedi discovers a hidden prophecy about Mortis and goes on a quest to understand it. This could involve facing challenges related to the balance of the Force that Mortis represents.
A great plot might be Katooni having to deal with a dark side - influenced Jedi who has turned against the Order. She has to find a way to either bring this Jedi back to the light or stop them from causing too much harm. Also, perhaps a story where she discovers an ancient Jedi artifact that holds the key to a great power, and she has to protect it from both the Separatists and those within the Republic who might misuse it.
A plot idea could be a story from the perspective of a minor character during the 'Deception' events. Say, a civilian on Coruscant who witnesses some of the events unfold but misinterprets them. This could lead to a whole chain of events where their false assumptions create new problems or solutions in the Star Wars universe. Also, a plot could revolve around a Sith trying to use the deception for their own gain, but getting caught in a web of their own making.