In some fanfiction, Hiccup discovers a long - lost dragon training technique. This leads to him and Toothless developing an even stronger bond and being able to perform incredible feats together. They then share this new knowledge with the rest of Berk, changing the way dragon training is done.
There might be a fanfiction where Hiccup, as the dragon master, has to train a group of young dragons and their riders. It could involve a lot of challenges like dealing with the different personalities of the dragons and the inexperience of the riders. He uses his unique bond with Toothless to inspire the others.
One interesting story could be about Hiccup exploring a new, uncharted island with Toothless and encountering a rare, magical dragon species. They have to figure out how to communicate with it and earn its trust.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of HTTYD fanfictions. Just search for 'Hiccup dragon master' and you'll get a bunch of results.
A more complex plot could be that a dark force is corrupting the dragons, and Hiccup, as the Dragon Master, has to find the source of this corruption. He has to use his skills and the bond he has with his dragons to not only stop the corruption but also save the dragons that have already been affected.
One popular 'HTTYD Hiccup is a Dragon Shifter' fanfic could be 'The Dragon Within Hiccup'. It explores how Hiccup's new ability as a dragon shifter changes his relationship with Toothless and the other dragons. Another might be 'Hiccup's Shifting Destiny' which delves into the challenges he faces while hiding his new form from the village at first.
A great HTTYD half - dragon fanfiction could be centered around a half - dragon's discovery of their heritage. They are raised as a normal human in a Viking village but start to notice strange abilities. As they explore their dragon side, they find a long - lost dragon family and must decide whether to stay with their human family or embrace their newfound dragon kin. Along the way, they use their half - dragon abilities, like being able to communicate with dragons on a deeper level or having enhanced strength and speed, to protect both their human and dragon families from common enemies like dragon hunters.
In some 'httyd oc dragon fanfiction', an oc might be from a different tribe that has a completely different way of training and living with dragons. The story could detail the cultural differences and how the oc's perspective on dragons changes when they interact with the main characters from the known 'httyd' world.
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.
Some fanfictions focus on their early days of getting to know each other. For example, a story where Hiccup is trying to teach Astrid more about Toothless and she is initially hesitant but then becomes fascinated, leading to a cute and heart - warming relationship development.
One idea could be a story where Hiccup discovers a new type of dragon that has unique abilities. He then has to learn how to befriend and ride this dragon while also facing challenges from other dragon riders who are jealous of his new discovery.
One interesting 'hiccup the dragon prince fanfiction' could be about Hiccup forming an unexpected alliance with the Dragon Prince. Maybe they team up to face a common enemy that threatens both their worlds.
A plot point could be a misunderstanding. Maybe Astrid sees Hiccup spending a lot of time with a new female dragon rider and gets jealous. This causes a rift between them, but then they have to work together to save Berk from a new threat. During this, they clear up the misunderstanding and their love becomes stronger.