There are often crossovers with other fantasy universes. For example, in some 'httyd crossover fanfic', the Vikings from httyd meet the characters from 'Narnia'. The contrast between the two worlds, one with dragons and the other with magical creatures like centaurs and fauns, makes for a really engaging story. It can bring new adventures and challenges for the httyd characters.
Some 'httyd crossover fanfic' involve modern - day settings too. There might be a story where Hiccup and his friends are transported to a modern city. They have to deal with things like cars, skyscrapers, and modern technology while still having their dragon - related skills. This type of crossover can be both humorous and exciting as they navigate this strange new world.
One popular idea is a httyd and How to Train Your Knight crossover. Imagine the dragons in a world filled with knights and castles. Another could be a crossover with a modern - day setting, like httyd characters in a big city dealing with new challenges. And there's also the idea of a crossover with a fantasy world like Middle - earth, where the dragons interact with different magical creatures.
There are fanfics that center around the growth and development of anthro dragons. They might start as outcasts in their own world and gradually find their place. These stories often involve character - building and the exploration of friendship. Some might also include elements of mystery, like uncovering ancient secrets related to the anthro dragons.
One popular theme is the combination of different kinds of magic. The ice magic from Frozen and the dragon - related magic in HTTYD. Another theme could be friendship across different worlds. Characters from HTTYD like Hiccup and those from Frozen like Anna forming an unlikely alliance. Also, the theme of discovery, as the characters from one world discover the wonders of the other world.
One popular trope is the 'fish out of water' situation. For example, a character from HTTYD finding themselves in the world of HOO and being completely confused by the Greek gods and demigods. Another is the 'team - up' trope, where the dragon riders and the demigods join forces to defeat a powerful enemy. A third one could be the 'culture clash' trope, with the Vikings from HTTYD having different values and ways of life compared to the modern - day (sort of) world of HOO.
One idea could be to have Toothless meet Jack Frost. Maybe Jack could try to ride Toothless and they could have an adventure together exploring the skies and the wintery landscapes. It would be cool to see how their different powers interact, like Toothless' fire against Jack's ice.
One idea could be that the dragons in HTTYD are attracted to the cold of Frozen's world and they fly there. The people of Arendelle are initially scared but then they learn about the dragons from the dragon riders. Another idea is that Elsa's ice powers somehow have an effect on the dragons, like making their fire breath turn into ice breath for a short time.
One idea could be that the dragon's fire power can be used to recharge the Transformers in some way. Another is that the Autobots could learn the concept of flying from the dragons and incorporate it into their own designs. Or perhaps the Decepticons try to capture the dragons to use their power for evil purposes, and the vikings and Autobots have to work together to stop them.
One interesting 'httyd fanfic' story could be about a new dragon species discovered in a hidden valley on Berk. The main character, a young Viking, forms an unexpected bond with this dragon, which has unique abilities. This story could explore their adventures together as they face challenges from other Vikings who are skeptical of this new dragon.
In some fanfictions, Hiccup and Anna might team up. Hiccup's knowledge of dragons and Anna's adventurous spirit could lead them on a quest. They might encounter a new type of dragon that has been affected by Elsa's magic, and they have to figure out how to deal with it while also trying to get Elsa and Toothless to work together.
First, you need to understand the characters and worlds of both HTTYD and Frozen. Then, think of an interesting plot that can bring the two together, like maybe a dragon from HTTYD somehow ends up in the Frozen world. Next, start writing the story, focusing on how the characters from both universes interact with each other.