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.
Well, start with setting the scene. Maybe it's a sunny day on Berk when Astrid first realizes she's pregnant. She could be out with Stormfly and suddenly feel a bit off. Then, for the plot, you can include how she tells Hiccup. He might be overjoyed and a bit clumsy in his excitement.
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.
The fanfic could focus on Astrid's pregnancy journey that led to the birth. It might detail how she coped with the physical changes and the support she received from Hiccup and her friends. There could be a part where they prepare for the baby's arrival, like building a nursery or gathering supplies. After the birth, it could show the couple's joy and the celebration within the village, with everyone coming together to welcome the new life.
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.
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.
The unique relationship between Toothless and Astrid can be a big draw. Their different personalities, with Toothless being a dragon and Astrid being a strong - willed human, create an interesting dynamic. When written in a'sexy' way (while still being appropriate), it can add an extra layer of depth to their bond, like exploring unspoken feelings or new levels of trust.
One popular one could be 'The Lost Tales of Hiccup and Astrid'. It delves deeper into their relationship as adults, with new adventures in the Viking world.
The birth could strengthen the bond between humans and dragons further. Dragons might see the new baby as a symbol of hope for the future of their co - existence. They could become more protective of the village where the baby is born, as they feel a new sense of connection to the family.
You can try looking on fanfiction websites such as Archive of Our Own (AO3) or FanFiction.net. These platforms have a wide range of fanfictions, and you might be able to find some related to Toothless and Astrid from How to Train Your Dragon that are tagged as'sexy' or have elements of it in a non - inappropriate way.