A great plotline could involve them teaming up to fight a new Sith threat. The Sith has created a powerful dark side weapon that could destroy entire planets. Luke, with his Jedi skills, and Mara Jade, with her combat and strategic abilities, join forces. They have to overcome their differences and trust issues as they journey to the Sith's lair. Along the way, they also discover a long - lost Jedi technique that helps them in their final battle.
Another plotline might be a story set after the fall of the Empire. Luke and Mara Jade are trying to help rebuild the galaxy. They encounter a group of warlords who are causing chaos. Luke uses his Jedi powers to try and negotiate peace, while Mara Jade uses her street - smart tactics to gather intelligence. Their relationship develops as they work together to bring stability to the galaxy.
One interesting plotline could be their first meeting in a different context. Maybe instead of how it happened in the official lore, they meet during a smuggler's run. Luke is on a mission to retrieve an important Jedi artifact and Mara Jade, working undercover for the Empire at the time, is also after it. Their encounter could lead to a series of adventures as they battle pirates and other foes while trying to outwit each other.
There are some fanfictions that might explore such a scenario. However, it depends on different authors' creativity and the specific plotlines they develop. Some fanfic writers might be interested in exploring the relationship between Mara Jade and Luke Skywalker in such a context, but it's not a mainstream or canon storyline in the official Star Wars universe.
One great fanfiction could be 'The Bond of Skywalker and Jade'. It delves deep into their relationship, exploring how their Force sensitivities interact. Another is 'Luke and Mara: A New Adventure' which takes them on a journey across the galaxy to face a new threat. There's also 'Mara Jade's Choice' that focuses on Mara's internal struggles regarding her feelings for Luke.
One of the common themes is definitely the exploration of the Force. Luke being a powerful Jedi and Mara Jade also having a strong connection to the Force, many fanfictions explore how they interact with the Force together. The theme of family also pops up. Even though they don't have a traditional family at first, they create a sense of family with each other. And of course, the theme of good vs. evil is there as they are often pitted against dark forces in the galaxy.
In certain fanfictions, their shared experiences of loss bring them closer. Both have lost a lot in their lives. Luke lost his family and mentors, and Mara Jade lost her connection to the Empire. This common ground makes them more empathetic towards each other. They support each other in their personal growth, with Luke helping Mara Jade explore the light side of the Force and Mara Jade teaching Luke some practical survival skills that she learned during her time in the Empire.
One possible plot could be them going into hiding to protect the unborn child from their enemies. Since they are both important figures in the Star Wars universe, there would be many who might want to harm the child for various reasons, like power or revenge.
One possible storyline could be that they face challenges from the dark side while Mara is pregnant. Maybe some remnants of the Empire try to target them because they see the unborn child as a potential threat or a powerful force for the light side. They would then have to go into hiding and rely on their friends and allies to keep them safe.
One interesting plotline could be Luke Skywalker being mysteriously transported back in time to the Clone Wars era. He could then use his Jedi skills, which he learned in his own time, to influence the battles in unexpected ways. For example, he might teach some Clone Troopers unique combat techniques.
One plotline could be that Luke discovers an ancient dance form on a remote planet that has some sort of connection to the Force. He then spends time learning and perfecting this dance, which in turn enhances his understanding of the Force in a new way.
One great piece of fanfiction could be 'Luke and Mara's Adventures Beyond the Stars'. It delves into their relationship as they face new threats in the galaxy. Another is 'Mara Jade: The Lost Years with Luke' which explores their time together during a period not much shown in the official canon. There's also 'Luke and Mara's Galactic Love Story' that focuses on the romantic aspect of their relationship.
Sith cults could also be antagonists. They might sense the power of the unborn child in the Force and want to turn it to the dark side. They could launch attacks on Luke and Mara to either kidnap Mara or influence the unborn child through dark side magic or the Force.