One idea could be to focus on how Astrid and Hiccup prepare for the baby. They might start building a new addition to their home on Berk. Hiccup could be super protective, while Astrid is determined to still be involved in dragon - related activities as much as she can until she can't anymore.
Perhaps a fanfiction could explore the reactions of their friends. Toothless might be especially curious and try to be around Astrid all the time. The other dragon riders could be excited and offer different kinds of help, like bringing special items for the baby from their travels.
One common theme is the relationship between Astrid and Hiccup. Their dynamic changes as they prepare for parenthood. Hiccup may become more nurturing and Astrid might show a softer side. Another theme is the anticipation of the new baby in the village. The villagers might start making preparations, like building a new crib or knitting baby clothes.
There would be a shift in their dynamic as they prepare for a family. Hiccup, who is used to being adventurous, would have to focus more on home and stability. Astrid, while still strong - willed, would become more nurturing. They would need to find a new balance in their relationship, between their old selves and their new roles as parents - to - be.
Astrid's character could develop in many ways. She may become more empathetic towards the other mothers in Berk. Before, she was mainly focused on her warrior duties, but now she can relate to the women who have to take care of their families. She might also learn to rely on others more, especially Hiccup, as she goes through the physical and emotional changes of pregnancy.
One interesting plot idea could be Hiccup and Astrid going on a secret adventure to a new, uncharted island. They face new dragons and have to work together to survive. Another could be a story where they have to deal with a rift in their relationship due to a misunderstanding, like Astrid thinking Hiccup is spending too much time with a new dragon rider. A third idea is a time - travel plot where they go back in time and have to change something in Berk's history to save the future.
She could be injured by a new type of dragon that no one has seen before. This would lead to a story where the riders have to study this dragon to find a way to cure Astrid. For example, they might discover that the dragon's venom has a unique antidote that can only be found in a certain part of the archipelago. Hiccup would be desperate to find it and in the process, learn more about the new dragon and its behavior.
One idea could be that Astrid discovers she's pregnant during a time of relative peace in Berk. She initially tries to keep it a secret from Hiccup because she's not sure how he'll react. As the story progresses, she starts to show signs and has to face the reality of sharing the news. Meanwhile, the village is preparing for a new celebration, and Astrid is worried about how the pregnancy will affect her role in it.
In many HTTYD fanfictions where Astrid is pregnant, it often explores how she and Hiccup handle this new chapter in their lives. It could involve Hiccup being overly protective, or Astrid trying to still be as independent as she used to be while dealing with the physical changes. For example, she might continue to train dragons in a more limited way, much to Hiccup's worry.
One idea could be exploring how they adjust to the new responsibilities. Hiccup might be worried about protecting his family while still leading the village. Astrid could be determined to train their future child to be a great dragon rider from an early age.
One possible title could be 'Astrid and the Male Reader: A HTTYD Adventure'.
There is also 'Hiccup and Astrid's Adventure'. This one takes them on a journey to a new land. The way it describes their interactions and how they rely on each other is really engaging. The author has a great writing style that makes you feel like you're right there with Hiccup and Astrid during their adventure.