I really liked 'The Time - Traveling Skywalkers'. It's a story where all four characters are caught in a time - travel anomaly. They end up in different points in time relative to each other. Padme gets to see a future where her children have grown up strong despite all the hardships. Anakin has to face his past self and tries to guide him away from the dark side. Luke and Leia use their knowledge of the future to try and make the galaxy a better place in the past. It's a really engaging read.
One great storyline could be a 'what if' scenario where Anakin doesn't turn to the Dark Side. In this, he and Padme raise Luke and Leia together. The twins grow up with their father's Jedi training and the family lives in harmony, facing the challenges of the galaxy as a united front.
Here's another idea. Suppose there's a threat to the galaxy that can only be stopped by using a long - lost technique that Padme knew about. Luke and Leia, with the help of Anakin's spirit, embark on a quest to find out about this technique. They face many challenges, including political intrigue and dark side threats, all while coming to terms with their family's complex history.
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.
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.
There are some fanfictions where the time travel is not just about changing the past, but also about learning from it. For instance, Luke travels back to the time of his father's youth. Instead of trying to directly change Anakin's path, he tries to understand the root causes of his fall. He then takes this knowledge back to his own time to better prepare the Jedi order for future threats. And Leia, when she travels back, might focus on building alliances that could have prevented the rise of the Sith in the first place. This kind of plot adds depth to the characters and the overall Star Wars universe.
You could also explore their relationships in a post - apocalyptic Star Wars setting. Suppose there has been a great war that has changed the galaxy. Luke, Leia, Anakin (if redeemed) and Padme (if alive) have to come together and rebuild their family while also trying to restore order to the galaxy. Their relationships would be tested and strengthened in this new and difficult situation.
In a time - travel scenario, Anakin and Luke's relationship could be transformed. Luke could finally understand his father's struggles more intimately by being present in the past. Padme and Leia might form a stronger bond as well, with Padme being able to mentor Leia in ways she couldn't before. Their relationships would be shaped by the new shared experiences in different time periods and the knowledge they gain from those travels.
Perhaps it's a time - travel scenario in the fanfiction. Luke and Leia, having discovered a way to travel back in time, meet their parents. Anakin would be shocked to see his grown - up children, and Padme would be in awe of the strong Jedi and princess they have become. They could exchange stories of their lives, with Luke and Leia learning about their parents' early days.
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.