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.
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.
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.
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.
Sure. There's a fanfiction where Luke discovers a hidden Sith temple that has the power to reverse the light - dark side balance in a person. He enters out of curiosity but gets trapped. The temple starts to slowly turn him to the dark side. As he changes, his friends sense it and have to decide whether to try to save him or destroy him, which is a really unique take on the concept.
Maybe in the fanfiction, Luke witnesses something so devastating that he loses faith in the Jedi way. For example, if the Jedi Order fails to prevent a great catastrophe. This could push him towards the Dark Side as he seeks a more radical solution to bring order. He might start using aggressive and unethical means, like Vader did, believing it's for the greater good.
There could be. Fanfiction writers love to take established characters like Luke Skywalker and put them in unexpected situations. A 'kidnapped' scenario might be used to explore different aspects of his character. Maybe it's a story where he's kidnapped by a new, mysterious force in the galaxy, and his friends have to rescue him. It's all about the creativity of the fans who write these stories.
Well, one possibility is that Luke Skywalker could use his Jedi powers to help the Avengers in combat. His lightsaber skills and ability to use the Force would be a great asset against powerful villains. For example, he could deflect energy blasts from enemies like Ultron, much like he deflected blaster bolts in the Star Wars universe.