Luke's friends from the light side could also be important. Characters like Leia, Han Solo, or Chewbacca. Their reactions to Luke's turn and their attempts to bring him back would be significant aspects of the story. There could also be new characters created specifically for this novel, perhaps some Jedi who were thought to be dead but are actually in hiding and oppose Luke's new path.
In many Star Wars fanfictions, a 'Dark Luke Skywalker' is a fascinating concept. It often shows a different path Luke could have taken. Maybe if he had given in to the dark side during his training or due to some great loss. This version of Luke can be extremely powerful and menacing, with a different set of abilities compared to his canonical self.
One of the main themes could be the struggle between good and evil. Luke Skywalker is typically a symbol of the light side, so exploring his journey towards the dark side would likely involve his internal battle with his own moral compass. Another theme might be the allure of power that the dark side offers and how it can corrupt even the most noble of characters like Luke.
One interesting 'Luke Skywalker dark side' fanfiction could be where Luke turns to the dark side after being constantly betrayed by the New Republic. In this story, he might use his newfound dark side powers to take revenge on those who he feels have wronged him. He could form an alliance with remnants of the Empire and become a powerful and feared Sith - like figure in the galaxy.
One popular 'Dark Luke Skywalker' fan fiction is 'The Fall of Skywalker'. It explores a scenario where Luke succumbs to the dark side after a series of tragic events. Another one could be 'Dark Apprentice Luke' which shows him as a powerful Sith - like figure. There's also 'Luke's Descent into Darkness' that details his journey towards the dark side in a very engaging way.
Some fanfictions depict Dark Luke Skywalker in an alternate universe where he turns dark much earlier in his life. Maybe due to a different event like the death of Obi - Wan Kenobi in a more brutal way during their first encounter. This changes his entire trajectory and he becomes a powerful and feared Dark Lord, causing chaos across the galaxy.
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.
In fanfiction, Dark Luke Skywalker's character can develop in various ways. Sometimes he starts off as a conflicted figure, gradually succumbing more and more to the dark side. His power grows as he delves deeper into Sith teachings or his own dark interpretations of the Force.
It could be the remaining Jedi. Since Luke has joined the dark side, the Jedi who still uphold the light side would be his natural antagonists. They would see him as a threat to all they stand for and would try to stop him from spreading the influence of the dark side. For example, Leia, if she still adheres to the Jedi teachings, would be in direct opposition to Luke.
One possible plot could be that Luke is lured by the power the dark side offers. Maybe he gets frustrated with the slow progress of the light side in bringing order to the galaxy. He might see the Sith as more efficient in getting things done. For example, if the Republic is still facing numerous threats and the Jedi are tied by their code not to take extreme measures, Luke could be tempted to cross over.