One common theme could be the challenges of impending parenthood. Sans, being a unique character, might face these challenges in his own special way, like trying to balance his usual lazy attitude with the responsibilities of having a child on the way.
Their relationship can develop through shared responsibilities. As they prepare for the baby, they'll have to rely on each other more. Sans might take on more tasks to ease Frisk's burden, and this can strengthen their bond.
I'm not really into that kind of fanfiction, but you can try looking on fanfiction - specific websites like Archive of Our Own. There might be some unique takes on the idea there.
In 'Undertale Pregnant Sans' fanfiction, a frequently seen theme is the relationship dynamics. How Sans' relationships, whether it's with his friends or family (if applicable in the fanfiction's interpretation), are affected. There might also be themes related to the challenges he faces during the pregnancy, like dealing with potential threats in the Underground while being in a vulnerable state. Also, some fanfictions might explore the idea of Sans preparing for the new life that's coming, which could involve everything from gathering resources to making emotional preparations.
First, know the characters well. Understand sans' personality traits and how they might be affected by this unique situation. Then, create a believable plot. Maybe start with how the pregnancy came about.
One common theme could be the challenges of unexpected pregnancy. Since it involves a unique pairing like'reader x sans', there might also be themes of how different species or beings handle pregnancy. Another theme could be the relationship development between the reader and sans during this life - changing event.
There might be some out there. You could start by checking popular fanfiction websites like Archive of Our Own. Just search for'reader x sans pregnant' in their search bar and see what comes up. However, the quality can vary greatly.
I'm sorry, but I don't have specific 'Undertale Pregnant Sans' fanfiction to recommend directly. You could try searching on popular fanfiction websites like Archive of Our Own (AO3) or Fanfiction.net. They usually have a large collection of Undertale - related fanfictions, and you might be able to find what you're looking for by using relevant keywords in their search bars.
When writing a'sans pregnant' fanfic, it's crucial to create a believable plot. You could explore how the other characters in the Undertale world would react to Sans being pregnant. Also, think about the challenges he would face. For example, would he still be able to do his usual activities? How would his friends support him? You can build on these ideas to create a rich and engaging story.
A plot idea could revolve around the discovery of the pregnancy. Maybe it was unexpected, and they initially panic. But then, as they start to think about it more, they get excited. They could start making plans like decorating a nursery in their unique Underground home. There could also be a plot where they face some sort of danger during the pregnancy that they have to overcome together.