Well, it could be that Hiccup is cursed by an evil sorcerer who wants to turn him into a dragon as a form of punishment. But as he turns into a dragon, he finds that he has a new connection with the dragon world. He starts to see things from a dragon's perspective and uses this to bring peace between humans and dragons in a whole new way.
There could be an old dragon that has been in exile for a long time. This dragon might see Hiccup as a threat to its plan of taking over the dragon kingdom. So it tries to stop Hiccup from fully becoming a dragon or tries to use his new form for its own evil purposes.
The plot might start with Hiccup having a strange encounter, like stumbling upon a hidden cave with a magical artifact. This artifact could be the key to his transformation into a dragon god. As he becomes more dragon - like in his powers, he could gain the ability to communicate with dragons on a whole new level, understanding their deepest thoughts and feelings. And he would surely have to use these powers to protect Berk from threats that normal human - dragon alliances couldn't handle.
You could start by imagining unique powers and abilities for Hiccup as a dragon god. Maybe give him the power to control elements or communicate with all dragons telepathically.
Hiccup's relationship with his father (if his father is still alive in the fanfiction) would be complex. His father might be proud of him for achieving such a powerful status, but also worried about how the other tribes would react. Hiccup would also have a different relationship with the dragons in general. He would no longer be just a friend to them, but a leader, a dragon god. This could lead to some dragons being more submissive to him, while others might test his new authority.
In 'hiccup the dragon fanfiction', one aspect could be the different dragon species and their characteristics. Hiccup might interact with various dragons, not just Toothless. It could show how he learns to communicate and cooperate with different types of dragons. Also, it might include some emotional parts, such as the bond between Hiccup and his dragon when they are in difficult situations, like being separated or facing a life - threatening danger.
Well, when Hiccup is a dragon in fanfiction, it could be because of an ancestral connection or a mysterious experiment. This could open up new storylines and allow for exploration of his identity in a completely different way. Maybe it's a way to show his ultimate empathy and unity with the dragon species.
One idea could be that Hiccup's transformation into a vampire gives him enhanced abilities like super speed and strength. This could make him an even more formidable dragon trainer as he can keep up with the dragons better. He might also have to deal with the thirst for blood, which could be an interesting internal struggle. Maybe he tries to find a way to control it without harming anyone, like finding a substitute for blood.
They might develop their relationship through shared experiences. For example, if they both get lost in an uncharted area, they have to rely on each other to survive. The half - dragon could use its natural instincts to find food and shelter, while Hiccup uses his intelligence to figure out how to get back home. This mutual dependence would strengthen their bond. Also, they could communicate through body language and simple sounds at first, gradually developing a deeper understanding of each other as time passes.
There could be Toothless. Even though Hiccup is now a dragon, his connection with Toothless from his previous human life might still be there. Toothless could play a crucial role in helping Hiccup adapt to his new form.