One common theme is the blend of magic and non - magic elements. Since Jacob is a Muggle and Queenie is a witch, their married life often involves showing how magic can be integrated into an ordinary life. For example, Queenie might use magic to clean the house while Jacob bakes in the kitchen.
There's also 'Queenie and Jacob's New Beginning'. In this fanfiction, they get married in a small, intimate ceremony. It focuses on how they deal with the reactions of their respective families and friends. Queenie's sisters are initially a bit worried, but Jacob's charm wins them over. It also delves into how they start a business together, with Jacob's baking skills and Queenie's magic helping to attract customers.
In this fanfiction plot, Queenie and Jacob find out about the pregnancy early on. They are both thrilled but soon realize they need to deal with many practical issues. Jacob has to figure out how to balance his work at the bakery with taking care of Queenie. Queenie has to deal with her own magical issues during pregnancy. They also start to think about the future of their child in a world that is not always accepting. They face family drama as well, with some of Queenie's wizarding family being less than thrilled about Jacob being involved.
Here's a short fanfiction idea. Queenie discovers she's pregnant one morning. She tells Jacob, and he is initially speechless with happiness. As the pregnancy progresses, they find out the baby has some unique magical abilities that seem to be a blend of both their natures. They decide to keep this a secret for a while. Queenie uses her magic to create a special nursery, while Jacob works extra hard at his bakery to save up for the baby's future. Their love for each other and the unborn baby grows stronger every day.
Perhaps the fanfiction could focus on how Bella adjusts to the werewolf lifestyle. Since she was previously involved with vampires, her new married life with Jacob could be full of cultural and lifestyle differences. For example, she might have to get used to the pack's traditions and the way they interact with the forest around them.
One common theme is the overcoming of their initial rivalry. In the original story, they are sort of enemies, so in fanfictions where they get married, there's often a story about how they put aside their differences.
A common theme is the exploration of their unique bond. Since they come from different supernatural backgrounds, the fanfiction often shows how they make their relationship work despite the differences. Another theme could be family. They might face issues related to starting a family of their own or dealing with their extended families. For example, how Jacob's werewolf pack accepts Nessie and vice versa.
In Jacob and Nessie married fanfiction, often the authors like to delve into the emotional aspects of their relationship. It could show Jacob's protectiveness towards Nessie in a new light as her husband. The fanfiction might also include some sweet moments between them, like how they celebrate their anniversaries or special occasions. There could be a lot of creativity in imagining their home life, perhaps they live in a place that is a blend of both werewolf and vampire cultures.
One character could be Seth Clearwater. As a member of Jacob's pack, he could play an important role in their married life. Maybe he helps them out in times of trouble or is like a younger brother figure to their family.
Jacob's wolf pack would also have a range of responses. Some of the younger wolves might be excited for Jacob, seeing it as a new chapter for their pack. But the older, more traditional wolves might be worried about the implications of this union for the pack's future and their relationship with the vampires. Jacob would have to work hard to convince them that this is a positive step.