Well, obviously Luke himself is a key character. He is the one who is falling to the dark side, so his actions, thoughts, and decisions are central to the story.
There might be a dark side mentor. This character would play a crucial role in guiding Luke towards the dark side. They would use their knowledge of the dark side's power and manipulation techniques to influence Luke.
One main factor could be the influence of a powerful dark side figure. Such a figure might manipulate Luke's emotions, like his fear or anger. Maybe they prey on his insecurities about his abilities or his place in the galaxy.
The Emperor or some other powerful Sith lords would likely be involved. They would see Luke as a great prize to turn to the dark side and would use all their cunning and power to manipulate him. Yoda's spirit could also be present, trying to guide Luke from beyond the grave but perhaps being unable to prevent his fall. Han Solo might also play a role, either trying to rescue Luke or being a victim of Luke's new dark side - influenced actions.
In some fanfictions, Luke might fall to the dark side after being betrayed by his closest friends. For example, if he discovers that they have been hiding important information from him that he thinks could have saved lives. This sense of betrayal could push him towards the dark side as he feels abandoned by the light. Also, a powerful dark side user could use mind control techniques on Luke, slowly turning him over time.
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 some fanfictions, 'dark side Luke' might be paired with Palpatine. Palpatine, as a master manipulator, could have a role in Luke's fall to the dark side, and their partnership would be full of political intrigue and dark Force - related activities. Palpatine could use Luke as a tool to further his own evil plans, while Luke might be seeking more power from Palpatine.
Occasionally, comics depict Luke Skywalker having encounters or internal conflicts involving the dark side. But it depends on the specific comic storyline and context.
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 of the main themes is the struggle between good and evil within Luke himself. In these fanfictions, we see how his inner conflict plays out. Also, the theme of redemption might be present in some, where there is a possibility for Luke to come back from the dark side. And the exploration of the dark side's allure, like the promise of quick solutions to problems compared to the more difficult path of the Jedi.
Not sure exactly, but maybe in a special edition or spin-off 'Star Wars' comic. Sometimes these story developments happen in limited series or special story arcs. You might have to do some digging to find the right one.
There could be multiple reasons. Maybe he was betrayed by someone he trusted, or he was lured by the power the dark side promised. Also, his past traumas might have played a role in his decision.