One possible plotline could be that after facing great losses and betrayals, Leia starts to question the light side's values. Maybe the death of a close friend or the destruction of something she holds dear makes her vulnerable to the temptations of the dark side. She might then begin to explore the power that the dark side offers as a means to gain control and revenge.
It could be that Leia discovers some dark secrets within the Rebel Alliance or the Jedi Order itself. This discovery shakes her faith so much that she decides to turn to the dark side. For example, if she finds out that the Jedi have been hiding information or using unethical means, she might think that the dark side is a better alternative in a corrupt galaxy.
One possible scenario could be that Leia is manipulated by a powerful dark side user. Maybe through false promises of power or a way to protect her loved ones in a distorted way. Another could be that she becomes disillusioned with the light side due to some great loss or perceived betrayal within the light side forces.
It could be a new, powerful dark side user created specifically for the fanfiction. This character might have a vendetta against the Skywalker family and sees turning Leia as a way to get revenge on Luke and Anakin. They could use Leia's insecurities and her desire to protect her loved ones against her.
One possible plotline could be Windu's internal struggle as he is gradually lured to the dark side. Maybe he starts to question the Jedi Code more and more as he experiences certain events or is influenced by a powerful dark side figure.
In some rey falls to the dark side fanfiction, her turn could be due to a sense of betrayal. If she discovers some dark secrets about the Jedi Order or the Resistance, she might feel that the dark side is the only way to get true justice. For instance, if she finds out that the Jedi had some hidden, unethical practices in the past. Then she starts to embrace the dark side teachings and uses her powers in a more aggressive and self - serving way.
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.
One plotline could be Padme's discovery of a long - forgotten Sith artifact. The artifact has the power to corrupt those who come in contact with it. Padme, in her quest for knowledge and power to change the galaxy, finds and unlocks the artifact's power. Slowly, it starts to change her, making her more aggressive, power - hungry, and willing to sacrifice the well - being of others for her own ends.
One possible plotline is that Superman is tricked by an alien race into believing that Earth is a threat to the universe. So, he decides to use his powers to stop Earth from 'causing harm', which is really him going to the dark side as he's misinformed.
One possible plotline could be that the dentist has a secret addiction to causing pain rather than relieving it. Maybe they use their position to experiment on patients in unethical ways.
One possibility is that she becomes disillusioned with the Rebellion. Maybe she discovers some dark secrets within the Alliance that make her question their motives. For example, if she finds out that the Rebellion has been using unethical tactics in the fight against the Empire. This could push her towards the dark side as she feels betrayed by those she once trusted.
There are several ways this could happen in fanfiction. For instance, a time - travel plot could be involved. Luke or Leia could travel back in time to a point where they don't know each other as siblings yet and fall in love. Or there could be a situation where they are both stranded on a desolate planet for a long time. During that time, they rely on each other so much that their relationship deepens into a romantic one without realizing their true connection. Also, a misinformation plot where they are wrongly informed that they are not related could lead to a kiss. However, these plotlines often deviate from the core essence of the Star Wars story and are more about exploring 'what if' scenarios in the realm of fanfiction.