Well, in a 'Star Wars' fanfic where Luke joins the Empire, it could be a very dark and complex story. Imagine, Luke, the hero who was supposed to bring balance to the Force, now using his powers for the very regime that the Rebellion was fighting against. His relationship with Darth Vader would take a whole new turn. Instead of being adversaries, they could become some sort of allies, at least initially. This would shock the entire galaxy. The Rebellion would be in disarray, not knowing how to deal with Luke's defection. And Luke himself would be in a moral quagmire, as he would be serving an organization that was responsible for so much destruction and oppression.
If Luke joined the Empire in a fanfic, it would be a complete deviation from his original path. He might use his Force abilities to rise quickly within the Empire's ranks. However, his friends like Han and Leia would likely become his enemies, leading to intense and tragic confrontations.
In a 'Harry Potter joins Empire Star Wars' fanfic, Harry might find himself in the middle of the Galactic Empire. He could use his invisibility cloak to sneak around Imperial bases. His wand could be seen as a strange new weapon. And perhaps he would team up with some rebels, sharing his knowledge of magic to help them in their fight against the Empire.
In such a fanfic, there could be epic battles. The Empire's advanced weaponry like the Death Star might be used against Earth's defenses. Maybe the Rebel Alliance would also get involved, teaming up with Earth's forces to fight the common enemy.
This would be a huge twist. It might mean Luke is seduced by the dark side's power or has some ulterior motive for joining Vader. It could change the course of the entire story.
The plot could involve the original character (OC) being attracted to the Empire's power and order. Maybe the OC is from a chaotic planet and sees the Empire as a way to bring stability. They might start as a low - ranking recruit, facing challenges from other Imperials who don't trust outsiders. But as they prove their loyalty and skills, they rise in the ranks and get involved in important missions, like hunting down Rebel spies.
If Percy joined Luke, it might complicate the dynamics. Maybe they'd have to face new challenges together or deal with the reactions of other characters. It could really shake things up!
Well, in such a fanfiction scenario where Luke is the emperor, he could have a very different approach to ruling than the previous emperors. Luke, being a former Jedi, would likely try to eliminate the corruption that was associated with the Sith - ruled empire. He might establish a more just galactic government, with an emphasis on peace and knowledge, using his unique understanding of both the Force's light and dark aspects.
If Luke becomes emperor in Star Wars fanfiction, the galaxy could see a new era of peace and justice. He might use his Jedi powers to root out the remaining Sith influence and bring about a more harmonious coexistence among different species. He would also likely reform the Imperial systems to be more fair and less tyrannical.
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.
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.
If Luke never left, it would change a great deal. He was so important in uniting different groups within the Rebellion. His absence from the Jedi training might mean that the knowledge of the Force would be less widespread in the Rebellion. Also, his story of facing Vader was a turning point. Without that, Vader might not have had the change of heart that he did, and the fate of the galaxy could have been much darker.