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 way could be to show Padme gradually losing faith in the Jedi Order. Maybe she discovers some dark secrets within the Order that make her question their motives. For example, if she finds out that the Jedi have been involved in some unethical political manipulations in the name of peace. This could start to chip away at her idealistic view of the light side and nudge her towards the dark side.
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 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.
One possible plotline could be that Batman is tricked into joining the Dark Side. Maybe the Joker uses some elaborate mind - control device or false information to make Batman believe that the Dark Side has the right way to bring true justice to Gotham. For example, he could be made to think that by using more extreme and violent methods, he can finally stop all the crime in the city once and for all.
In this kind of fanfiction scenario, it would be a huge shock to the Star Wars universe. Obi - Wan is known for his strong connection to the light side. If he turned, perhaps his relationship with Anakin would have been drastically different. Instead of being a mentor, he might have been a rival or even a corrupting influence on Anakin.
Well, if Obi Wan turned to the dark side in fanfiction, it would likely shake up the dynamics between him and the other Jedi. It might also change the outcome of many key battles and events in the Star Wars universe.
One possible plotline could be that Ahsoka feels betrayed by the Jedi Order. Maybe she discovers some dark secrets within the Order that make her lose faith in the light side. This could lead her to be lured by a powerful Sith Lord who offers her a new way of seeing things, and slowly she starts to embrace the Dark Side, using her skills in new and more aggressive ways.
One possible plotline could be that Rey finally succumbs to the dark side under Kylo Ren's influence. He might train her in the ways of the dark side, leading them to rule the galaxy together with an iron fist. Maybe they start by taking over the First Order and using its resources to spread fear and chaos.
One idea could be that Anakin's fall to the Dark Side causes him to try and make Padme a Sith as well. He might use his newfound power to manipulate her, believing that together they could rule the galaxy. For example, he could start by isolating her from her friends and allies in the Jedi Order and the Republic, making her more dependent on him.