One possible fanfic could be that Hiccup's transformation into a Dragon Toothcup is the result of a magical experiment gone wrong. Maybe a wizard in Berk was trying to create a new form of dragon - human bond and accidentally merged Hiccup with a special dragon toothcup. As a Dragon Toothcup, Hiccup could have unique abilities like being able to sense the emotions of dragons more acutely and communicate with them on a deeper level. His friends would be both shocked and intrigued, and they would have to figure out how to reverse the transformation.
One possible plot could be that Hiccup's transformation into a baby dragon is the result of a magic spell gone wrong. He then has to figure out how to reverse it while experiencing the world from a dragon's perspective. He might make new dragon friends who help him understand his new form and search for a cure.
Toothless would be extremely confused yet instinctively protective. He would curl around Hiccup to keep him safe from any potential threats. Astrid would be a mix of emotions. She would be worried about Hiccup's well - being and also frustrated that she can't communicate with him in the normal way. The other Vikings would have diverse reactions. The ones who were skeptical of Hiccup's dragon - friendly ways before might see this as a sign that his ideas were wrong all along. However, those who trusted Hiccup would try to support him in this strange new situation. They might start looking for any magical items or wise people in the village who could help reverse the transformation.
One idea could be that Hiccup turns into a dragon during a battle and uses his new form to surprise the enemy. He could fly faster and breathe a more powerful fire than any other dragon, leading his team to victory.
The plot could be that Hiccup finds a cursed dragon toothcup during one of his adventures. When he picks it up, he is immediately transformed. His friends think he's lost forever, but Hiccup in his new form tries to communicate with them. He discovers that he can hold dragon powers within the toothcup form. For instance, he can store and release dragon fire. With these new abilities, he helps Berk defend against a powerful enemy that has been threatening the village.
His relationship with Toothless would be very different. Toothless might be initially confused and a bit hesitant around Hiccup in his new form. But as time passes, they would develop a new kind of bond based on Hiccup having to adapt to being a dragon. With Astrid, it could be strange at first. Astrid might be both curious and a bit jealous of Hiccup's new dragon form. She would have to see Hiccup in a whole new light.
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.
Astrid would probably be very surprised at first. She might be a bit jealous of Hiccup's new appearance as a girl, but also curious about how this change has affected Hiccup's personality. Stoick would be shocked and might be a bit overprotective. He'd have to adjust to the idea of his son being in a different form. Snotlout would likely make some inappropriate jokes at first, but then gradually come to accept Hiccup as she is. And Toothless? He might be a bit confused at first, but his bond with Hiccup would likely remain strong regardless of the physical change.
With his human friends, it would be really tough. They might be scared of him at first. Astrid, for example, would be conflicted. She was attracted to Hiccup as a human, but now he's a dragon. She would have to overcome her fear and try to find a way to communicate with him. And Hiccup would feel isolated from his human friends, longing for the connection they once had.