In fanfics, Astrid could be mad at Hiccup for various reasons. One reason could be that he breaks a promise to her. For instance, if he promised to help her train a difficult dragon but then backs out because he got distracted by another project. This would make Astrid, who values loyalty and commitment, mad at him. Another reason might be miscommunication. If Hiccup doesn't clearly express his intentions or feelings, it can lead to misunderstandings and Astrid's anger.
One possible fanfic could be that Hiccup's transformation into a Dragon Toothcup is the result of a magical experiment gone wrong. Maybe a wizard in Berk was trying to create a new form of dragon - human bond and accidentally merged Hiccup with a special dragon toothcup. As a Dragon Toothcup, Hiccup could have unique abilities like being able to sense the emotions of dragons more acutely and communicate with them on a deeper level. His friends would be both shocked and intrigued, and they would have to figure out how to reverse the transformation.
I'm not sure specifically if there is a 'hiccup haddock pregnant' fanfic. There are so many fanfics out there in the vast world of fandom, and it might be difficult to determine the existence of one with such a specific theme without doing a thorough search on fanfic platforms.
The setting is important too. It could be the familiar Berk or some new, uncharted lands. A different setting can bring new challenges and opportunities for Hiccup. For instance, if it's in a land filled with ice and snow, Hiccup has to deal with the harsh environment as well as any threats that might lurk there. Also, the other characters from the original story, like Astrid or Stoick, might play different roles in the fanfic, either supporting Hiccup or creating conflicts for him.
Some dragons are more aggressive by nature. In fanfics, these dragons might be more likely to attack any potential threat to Hiccup without hesitation. For example, a dragon like Hookfang might be quick to breathe fire at anyone who gets too close to Hiccup in a menacing way. On the other hand, a more gentle dragon like Meatlug might use her size to block Hiccup from harm rather than being as confrontational.
They might start off as strangers. Nubless could be a bit cautious around Hiccup at first, while Hiccup is his usual curious self. They could slowly get to know each other through shared tasks like taking care of dragons or exploring new lands.
There are many great Astrid and Hiccup fanfics out there. You can start by looking on fanfiction platforms like Archive of Our Own. Search for stories that focus on their adventures together, their relationship growth, or how they face challenges in the How to Train Your Dragon universe. Some fanfics might explore their teamwork in training dragons or their personal development as leaders in Berk.
Well, their relationship in the original series is very appealing. Fans love to explore more about their relationship in fanfics. They are two very different characters, Hiccup being the more cerebral one and Astrid the brave warrior, and seeing how they interact in different scenarios is fascinating.