Well, aside from Jareth and Sarah, there could also be other characters from the original story that play important roles. For example, the goblins might be characters that are constantly around. They could be either helpful or cause trouble for the newly married couple. Also, Sarah's friends or family from the human world might be in the story. They could be trying to understand her new life with Jareth, or perhaps be worried about her being in the magical world. And who knows, there might be some new magical characters created just for this fanfiction to add more drama and storylines to their married life.
Perhaps a plotline where they have to deal with the differences in their worlds. Sarah comes from the human world and Jareth from the magical realm. Their married life could be about finding a balance between the two, like how they decorate their home, half with human items and half with magical ones.
One possible plotline could be Sarah's initial resistance. She might try to find ways to escape the forced marriage, leading to a series of adventures within the Goblin Kingdom. Another could be Jareth slowly realizing his feelings for Sarah during the course of the forced marriage and trying to win her over in his own, rather complex way.
Yes, there might be some. You can start by looking on fanfiction websites like Archive of Our Own. Just search for 'Jareth and Sarah forced married' in the search bar and you'll likely find several stories. However, the quality can vary a great deal.
The relationship might become more intense. With the pregnancy, they have to rely on each other more. Jareth may show his softer side as he takes care of Sarah, and Sarah might start to see him in a new light, beyond the intimidating Goblin King.
A common theme is the exploration of their unspoken connection. Since in the original there's a certain tension between them, fanfictions often expand on that, like in 'The Unspoken Bond' where it's all about their unacknowledged feelings for each other.
One common theme is the power dynamic between them. Since Jareth is a powerful Goblin King and Sarah is a mortal girl, exploring how their relationship develops in terms of power is popular.
In fanfiction, the idea that they come from two completely different realms, the human world and the Goblin Kingdom, adds to the allure. Their relationship can be seen as a bridge between these two worlds, and how they navigate the cultural and magical differences is fascinating. For example, in some stories, Sarah has to learn the ways of the Goblin Kingdom to be with Jareth, and Jareth has to understand human emotions better. This dynamic makes for a rich and engaging story.
There could be some out there, but a lot of fanfiction platforms have rules against explicit content. You might have better luck looking for more general Jareth and Sarah fanfiction on Archive of Our Own (AO3). It has a large collection, and you can filter by different themes and ratings to find something that suits your taste, but stay away from inappropriate stuff.
They are a popular pairing because of the strong dynamic between them in the original story. Dark Jareth is a mysterious and powerful character, and Sarah is a brave girl. The contrast makes for an interesting relationship in fanfiction.