Often, there's a plotline where Luke discovers a dark secret within the Jedi Order. His attempts to expose it make the other Jedi see him as a threat and label him a traitor. For example, if he finds out that the Jedi have been involved in unethical experiments or have a hidden agenda that goes against the values they preach. He then has to fight against his former allies while trying to set things right, which gives the impression of him being a traitor.
One common plotline could be that Luke is lured to the dark side by promises of power. The dark side characters might convince him that he can better protect the galaxy with their power. Another plotline is that he is wrongly accused of a crime against the Jedi Order or the Republic, which makes everyone think he's a traitor.
Some fanfictions might have a plot where Luke's loyalty is tested when he meets an old friend or family member who has turned to the dark side. In his efforts to save them, he may make decisions that seem traitorous to the Jedi. For instance, he might help them escape from Jedi custody or cover up their misdeeds. This internal conflict between family/friendship and his Jedi duties can lead to the perception of him as a traitor.
In certain fanfiction, Luke's actions might be misinterpreted, leading to the idea of him being a traitor. For example, if he discovers a long - hidden truth about the Jedi and the Sith that challenges the established order. His attempts to expose this truth could be seen as traitorous by those who want to maintain the status quo. He might also be forced into situations where he has to work with the 'enemy' to save his friends or the galaxy, and this cooperation is wrongly construed as betrayal.
One common theme is the struggle between the light and dark within Luke. Even as he turns dark, there are often remnants of his former self trying to break through. Another theme is his relationship with the other characters, especially how they view him now that he has fallen. For example, his friends might be in denial at first.
A really cool fanfiction idea could be Luke Skywalker leading a group of young Jedi in a post - Return of the Jedi world. He has to train them while also facing new threats that have emerged in the galaxy. This could show his wisdom as an older Jedi and how he passes on the Jedi teachings.
One interesting plotline could be Luke and Leia going on a joint mission to discover more about their mother. They might face various challenges along the way, like encountering an ancient Sith artifact that tests their Jedi abilities and their bond as siblings.
One plotline could be that Luke discovers an ancient dance form on a remote planet that has some sort of connection to the Force. He then spends time learning and perfecting this dance, which in turn enhances his understanding of the Force in a new way.
One reason is the potential for new relationships. In 'Star Wars Rebels Luke' fanfictions, we can see Luke form bonds with characters from the Rebels series that he might not have interacted with in the main canon. This creates new and exciting storylines, like Luke training with Ezra or having philosophical discussions with Hera. It adds a new layer to the Star Wars universe we know and love.
There could be a fanfiction where Leia and Luke go on a secret mission. During this mission, they rely on each other's skills, Leia's leadership and Luke's Jedi powers, and they face many challenges together. This could include battles against new enemies and solving complex puzzles.
One possible fanfiction could be about Luke being abandoned on a desolate planet as a child. Maybe he has to fend for himself and discovers his Force abilities on his own without the guidance of Obi - Wan or Yoda at first. This could lead to a very different journey for him, perhaps making him more independent and distrustful of others.
A really good fanfiction could involve a time - travel scenario where Bakura, Luke, and Mara are sent back in time. They have to navigate the different eras of the Star Wars universe while also trying to figure out how to get back to their own time. This would give the author a chance to explore different aspects of the Star Wars lore and how these three characters would interact with historical figures and events.
One possible reason could be a misinterpretation of his actions. Maybe he made a decision that others in the fanfiction misconstrued as betrayal, like his attempts to reach out to the enemy in an effort to bring peace but it was seen as siding with them.