One could write a fanfiction where a mysterious Force - user creates a special bond between baby Luke and Leia. This bond allows them to feel each other's pain and joy. So when Leia is sad on Alderaan, Luke might start crying on Tatooine without really knowing why. And as they grow older, this bond continues to play a role in how they interact and support each other in the fight against the Empire.
Their relationship could be explored through shared dreams. Since they are both strong in the Force, they could have dreams of each other even as babies. In the fanfiction, these dreams could be a way for them to communicate on a deeper level, sharing emotions and a sense of comfort, even though they are separated physically.
Their relationship could be explored by having them go on a spiritual journey together. They might meditate in the Force and share their innermost thoughts and feelings, which they've never fully expressed before. This could deepen their bond in a very unique way.
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.
One way to develop their relationship uniquely is through the Force. Anakin could discover that Baby Leia has a very strong but unrefined connection to the Force. He then takes it upon himself to gently guide her, not in the traditional Jedi way, but in a more personal and emotional way. This would create a deep and different kind of connection between them. Also, Anakin might share his own experiences of growing up as a slave with Baby Leia in a way that she can understand as she grows older, which would strengthen their bond on a very personal level.
In a fanfic, their relationship could be explored by having Leia search for information about Padme. This journey of discovery could reveal how much they are alike, and also how Padme's legacy has influenced Leia's life and choices.
In the original Star Wars canon, Luke and Leia are siblings, so a romantic kiss between them goes against the nature of their relationship. However, in fanfiction, some might explore this in an alternate universe or what - if scenario. But it can be quite controversial as it clashes with the established family bond in the official story.
Their relationship could develop uniquely if Darth Vader starts to have dreams about Baby Luke's future as a great Jedi. These dreams make him question his loyalty to the dark side. So he begins to secretly guide Luke in the ways of the Force, like leaving behind ancient Jedi texts for the baby to find when he's older.
A plot might also involve a young Rebel pilot who stumbles upon the hiding place of baby Luke and Leia. Instead of turning them over to the Rebellion right away, he decides to take matters into his own hands and protect them personally. He has to evade both Imperial and some over - eager Rebels who want to use the children as symbols, all while learning about the importance of family along the way.
There's 'Leia and Luke's Adventure' where they embark on a journey to find an ancient Jedi artifact. This fanfiction is full of action and also delves into their relationship as siblings who are both powerful in different ways.
One unique plot idea could be exploring an alternate universe where Luke and Leia discover their connection earlier and it creates a different dynamic in the fight against the Empire. Maybe they use their bond in a more strategic way, like Luke being able to sense Leia's thoughts during diplomatic missions and vice versa.
Yes, there are some out there. You can start by looking on popular fanfiction websites like Archive of Our Own. Some fanfictions might explore their relationship in alternate universes or expand on their emotional bond in a way that the movies didn't fully delve into.