One possible plotline could be Anakin, in a redeemed state, secretly protecting baby Luke from the remaining threats in the galaxy. He uses his remaining Force abilities to shield Luke from danger without revealing his identity.
Another plot could involve Anakin, in a sort of alternate universe scenario, being given a second chance to be a father to baby Luke right from the start. He has to learn how to raise Luke without the influence of the dark side, and this journey of redemption and fatherhood could be explored in great detail. It could show how Anakin's love for his son overcomes his past mistakes and how he imparts his knowledge of the Force to Luke in a positive way.
One interesting plotline could be Lorelai and Luke going on a spontaneous road trip together. They might discover new things about each other and their relationship deepens during the journey.
One possible plotline could be Anakin's redemption taking a different turn. Instead of dying, he lives and uses his newfound Light Side strength to help Luke rebuild the Jedi Order. He could become a mentor to the new generation of Jedi, sharing his experiences and knowledge, which is a far cry from his previous role as Darth Vader.
One possible plotline could be Anakin having to re - learn the ways of the Force as a child while also dealing with his past memories. Another might be how the other Jedi react to this de - aged Anakin, whether with suspicion or a sense of protectiveness.
Another plotline might be that Vader has a secret mission that requires Luke's help. They have to team up despite their differences, and along the way, they start to understand each other better. For example, Vader could be trying to stop a greater evil in the galaxy that even the Emperor doesn't know about.
A third plotline could be set in an alternate universe where Luke and Leia meet under different circumstances. For example, they could meet as children before they were separated. This would completely change the dynamic of their relationship and lead to a whole new set of adventures and character developments.
Some fanfictions might explore the idea of how having a baby changes Luke and Lorelai's relationship dynamic. They were already in love, but now they have this new life to take care of. There could be a plot where they struggle to find time for each other while also being completely devoted to their baby. It could also show how they support each other during the sleepless nights and all the chaos that comes with a new baby, strengthening their bond even more.
There could be a fanfiction where baby Luke Skywalker is visited by a mysterious Jedi in his dreams. This Jedi gives him some sort of premonition or a message about his future. It could be a Jedi who was friends with his father and is trying to guide Luke from afar, even at this young age.
Perhaps in the fanfic, Anakin losing his arm is a turning point. Padmé, seeing his pain and the path he might be headed towards, decides to take Luke and hide away. But Anakin, consumed by his own loss and the dark side tugging at him, tries to find them. This could lead to a cat - and - mouse type of plot where Padmé is constantly on the run, trying to protect Luke from Anakin who is slowly losing himself more and more.
Perhaps he goes back in time and decides to train himself better. He could focus on mastering his emotions from the start, which might change the entire course of the Star Wars saga. He might also try to save his mother in a more effective way, without succumbing to anger and hatred.
Some fanfictions explore their relationship in the context of the Jedi Council. Since Anakin was often at odds with the Council, and Aayla was more in - line with the traditional Jedi ways, it creates an interesting dynamic. Maybe Anakin has an idea for a new strategy in the war, and Aayla has to decide whether to support him or side with the Council, which can lead to a lot of character development.