One idea could be a story that focuses on Anakin's internal struggle between his love for Padme and his fall to the dark side as Darth Vader, while Luke and Leia unknowingly grow up in the shadow of their father's actions. It could explore how their lives might have been different if Anakin had not turned, and how they eventually come to terms with his true identity.
Perhaps a fanfic that delves into the time when Anakin was on the cusp of turning to the dark side. Padme could sense the change in him and tries to prevent it with the help of Luke and Leia from the future who somehow travel back in time. This would create a complex web of relationships and a race against time to save Anakin from the dark side.
The fanfic could be set during the Clone Wars. Anakin's dark side starts to emerge due to the stress and manipulation. Padme notices the changes in him. Meanwhile, Luke and Leia are prophesied to be the ones who can save the galaxy from the dark side that Anakin is falling into. It could show how their fates are intertwined even before they are born, with Padme trying to protect the future of her children and Anakin.
One idea could be that Luke and Leia time travel back to the time before their parents' relationship soured. They could try to prevent Anakin's fall to the dark side, which would in turn change the fate of their family. Their presence might also have unforeseen consequences, like disrupting the natural flow of the Force. Maybe they meet their younger selves as children, which would create some really interesting and complex scenarios.
A possible plot is a fanfic where Anakin, in his Darth Vader form, has a vision of a different future where he didn't lose Padme. This vision makes him question his loyalty to the dark side. Meanwhile, Luke and Leia are on a mission to rescue their father from the clutches of the Emperor. The story could be filled with emotional reunions and battles between the light and dark forces.
One idea could be a time - travel plot where Luke and Leia are sent back in time and meet their parents, Anakin and Padme, before Anakin's fall to the dark side. They try to prevent the events that led to the rise of the Empire.
Often, Anakin and Padme's love in fanfic is intensified. It might show Anakin's internal struggle with the dark side while still being deeply in love with Padme. Luke's love in fanfic could be about his love for the galaxy, his friends, and his family, which might also translate into a romantic love for someone special. Leia's love could be about her strong love for her people and her planet, and this could be intertwined with her romantic love for Han Solo or other potential love interests in fanfic.
The idea of redemption is a big one. Darth Vader's redemption at the end of Return of the Jedi is a powerful moment, and fanfics often expand on this. They might explore what led to his final choice, or how his family influenced his decision. Additionally, the exploration of the Force and how it connects all these characters is another common theme. It could be about how Luke and Leia develop their Force abilities differently, or how Anakin's relationship with the Force changed over time.
You can try fanfiction.net. It has a vast collection of Star Wars fanfics involving Anakin, Padme, Luke, and Leia. There are different genres and styles to choose from.
In 3D fanfic, Anakin and Padme's love can be quite dramatic. The 3D might make their passionate love seem more intense, with their scenes together having more visual impact. Luke and Leia's love as siblings can be shown as a strong and unwavering bond. It could be depicted as they stand by each other in various situations, and the 3D aspect can make these moments more vivid.