Well, Fishlegs would most likely interact with Hiccup. He's a friend and he'd probably be curious about how Hiccup is handling the change. Ruffnut and Tuffnut could also be involved. They might make jokes at first but then come to accept Hiccup. And Gobber! He's an important figure in Hiccup's life. He could offer practical advice on how to deal with the new body, like how to handle weapons or do tasks that were easier in his male form. He might also be a source of comfort for Hiccup during this confusing time.
Astrid is likely to be one of the main characters to interact with Hiccup. She might be initially very confused or even a bit jealous depending on how she perceives Hiccup's new form. Stoick, Hiccup's father, would also have significant interactions. He would probably be shocked at first but then try to support his child in this strange situation. And of course, Toothless. Their bond is so strong that Toothless would surely be involved, perhaps trying to understand what has happened to his rider.
Sasuke would definitely be one of the main characters to interact with Naruto. Their relationship has always been complex, and with Naruto as a girl, it could become even more so. Sakura would also interact a lot. She might be both jealous and intrigued by Naruto's new form. Kakashi too, as Naruto's mentor, would have to adjust to this change and guide 'her' in a different way perhaps.
Another character could be Astrid. In the fanfiction, she might play a role in Hiccup's journey to get stronger. She could be his training partner or offer advice based on her own skills and experiences. Also, there might be new characters introduced, like an old dragon trainer who has a lot of wisdom to share with Hiccup.
There could be some new characters introduced as well. Maybe a mysterious dragon rider from a far - off land who also has the ability to talk to dragons. This character could either be an ally or an antagonist to Hiccup, depending on their motives. Or perhaps an old dragon trainer who has long - forgotten secrets about the dragons' language that Hiccup has to discover.
One interesting plot point could be how Hiccup adjusts to the new physical form. For example, he might struggle with the different clothing styles and social expectations for girls in his world. Another could be the reactions of his friends. Some might be shocked at first, while others could be more accepting and help him through the transition. There could also be a plot point about how this change affects his relationship with Toothless. Maybe Toothless initially doesn't recognize him and Hiccup has to find new ways to bond with his dragon.
Astrid would definitely be a main character. She could be the one who helps Hiccup readjust to life in Berk after rehab. She might be a bit hesitant at first, but then realizes that Hiccup has truly changed for the better.
In this fanfiction, Hiccup is the central character as he takes on the task of taming the Red Death. Astrid could also be involved. She might be skeptical at first but later see the value in Hiccup's attempt. And the Red Death is the key character that the story focuses on taming. There could also be other Vikings in the background who either oppose Hiccup's idea or are in awe of his courage to take on such a dangerous dragon.
Well, obviously Hiccup would be one of the main characters. His character is central to the whole concept of refusing to kill dragons. Astrid could also be a main character. She might initially be on the side of the traditional view of killing dragons but gradually come to understand and support Hiccup's stance. Stoick, Hiccup's father, would be an important character as well. His position as the chief and his traditional beliefs would create a lot of conflict with Hiccup's new ideas. And of course, the dragons themselves, like Toothless, could be considered main characters in a sense. They are the ones that Hiccup is trying to protect and coexist with.
Obviously, Hiccup and Toothless would be central characters. Astrid might also be there, as she is an important part of Hiccup's life. Other dragon characters like Stormfly, Hookfang and the rest of the dragon riders' dragons would likely be involved too.
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.
Well, Astrid could potentially make Hiccup mad in fanfiction too. For instance, if she goes against Hiccup's orders during a crucial mission because she has her own ideas and doesn't trust Hiccup's plan. Also, the dragon hunters in fanfiction are always a source of Hiccup's anger. They are constantly trying to capture or harm dragons, and Hiccup, being the dragon lover he is, would get extremely angry at their actions. And sometimes, even Toothless, if he's written in a way that he's being overly stubborn and not listening to Hiccup, could cause Hiccup to get mad.