How Could Luke's Character Develop if He Joins the Dark Side in Star Wars Fanfiction?

If Luke joins the Dark Side, it would completely change the dynamic of the Star Wars universe. His friends would be shocked and heartbroken. Leia, for instance, would probably try to bring him back. The Rebellion would lose a great hope and the Empire might gain an unexpected and powerful ally. It could also lead to a different kind of struggle within the galaxy as those who once believed in Luke now have to face him as an enemy.

She would become more ruthless. Instead of being the hopeful and somewhat naive Rey we know, she would be calculating. For example, she might not hesitate to sacrifice a few for the sake of what she believes is a greater good. Her appearance would also change. Maybe she would start to dress in darker colors, and her eyes could take on a more menacing look. Her relationships would be different too. She would probably break off ties with her old friends from the Light Side, seeing them as obstacles to her new goals.

It could be the remaining Jedi. Since Luke is turning to the dark side, the Jedi who still uphold the light side values would be against him. They would see him as a threat to the balance they are trying to maintain and would try to stop him from fully embracing the dark side.

In the fanfiction, Luke could be influenced by his family ties to the dark side. If he discovers some hidden connection to Vader or Palpatine that he didn't know before, it might make him question his place on the light side. He could think that joining the dark side is a way to understand his true heritage better and gain more power to protect those he loves in a different way than the Jedi would allow.

A plot twist could be that Rey has a dark heritage she was unaware of. When she discovers this, she feels a pull towards the Dark Side. She may struggle with this newfound knowledge at first, but eventually give in. In the story, her transition to the Dark Side could cause chaos in the Star Wars universe. The Resistance would be shocked and some might try to bring her back. However, the Dark Side could give her new powers and a different perspective on the Force. She could then start to reshape the Sith ideology, creating a new form of the Dark Side that is more in line with her own beliefs, leading to a whole new conflict in the galaxy.

It could be a new Sith Lord created specifically for the fanfiction. This new character could be more powerful and devious than any before. He could be the one who lures Luke to the Dark Side and then becomes his enemy as they compete for power within the Dark Side hierarchy.

Another plot could involve a powerful Sith Lord who manipulates Luke. The Sith Lord could use Luke's insecurities, like his fear of not being strong enough to protect his friends. He could be tricked into believing that the Dark Side would give him the power he needs, and slowly turn to the dark side as a result.

His character would likely become more complex. He would have to make tough decisions as an emperor, which might make him more calculating and less impulsive. He may also grow more powerful in the Force as he has to deal with the responsibilities of ruling.

Luke joining the Empire in a fanfic would be a huge shift for his character. His naivete might be exploited by the Empire. He could be made to believe that the Empire's way was the only way to bring order to the galaxy. As he got more involved, he'd see the atrocities committed by the Empire. This would cause him to reevaluate his decision. His character development would then be about redemption, trying to make up for the wrongs he'd done while with the Empire. He might even try to use his position within the Empire to undermine it from the inside, which would be a very different kind of hero's journey from what we're used to in the Star Wars franchise.

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.