A common theme is the exploration of their cultural differences. Hungary has his own unique cultural traits and Prussia has hers, and in fanfiction, it's often interesting to see how these differences play out in their relationship.
There are some fanfiction communities on Tumblr as well. Some users might share or create their own stories about male Hungary and fem Prussia. You can search for relevant tags like '#malehungaryxfemprussia' or '#hetaliafanfiction' to find these stories. However, the content might be a bit more scattered compared to AO3.
A third theme could be the relationship between the two characters. The pregnancy could either strengthen their bond or create new tensions. It could show how they rely on each other more than ever, or it could expose insecurities and differences in their relationship as they face the challenges and joys of impending parenthood.
Friendship and loyalty are also common themes. Prussia and Hungary can be portrayed as friends who support each other through difficult times. In some fanfics, they might have to face challenges together, and their loyalty to each other is tested and strengthened. Also, there can be a theme of mutual respect. Given their different strengths and characteristics, they learn to respect one another in these stories.
I'm not sure if there are specific fanfics solely focused on Prussia and Hungary being pregnant. Fanfic topics can vary greatly, and while there might be some in the vast realm of fanfiction that touch on such concepts in the context of their relationship, it would require a detailed search through relevant fanfic platforms.
One common theme is cultural exchange. Prussia and Hungary have different cultures, and in fanfictions, they often explore each other's traditions, like Prussia introducing Hungarian to his military strategies or Hungary showing Prussia her folk dances.
There's also 'Prussia and Hungary: A Tale of Two Nations' which focuses on how their different cultures interact and how they gradually fall in love. It has some really cute moments like when Prussia tries to learn Hungarian dances to impress Hungary. It shows their relationship in a very heart - warming way, exploring not just the romantic aspect but also their political and cultural ties.
One popular 'Prussia x Hungary fanfic' could be 'The Prussian-Hungarian Alliance'. It delves into their relationship in an alternate historical setting where they have to work together against a common enemy. The story is filled with great character interactions and political intrigue.
One idea could be Prussia as a girl trying to break into the typically male - dominated military world in the Hetalia universe. She could face challenges and prejudices but also prove herself to be just as capable as the male characters.
First, do research on Hungary. Know about its geography, culture, and people. This will help you create an authentic setting for your fanfic. Then, develop interesting characters for the student and the Hungarian counterparts. Make their interactions engaging.