A fanfic could explore how Hiccup's transformation into a girl affects his friendships. Astrid might react in a complex way. At first, she could be jealous or confused, but then they could form a stronger bond. Also, Hiccup's father, Stoick, might have a hard time adjusting to his son becoming a daughter, which could add a lot of emotional depth to the story.
In this fanfic, Hiccup as a girl could bring new fashion and style elements to the Viking world. Instead of the traditional male Viking attire, she might start wearing something more unique. This could also influence other female characters in the story, and maybe even start a new trend in the village. And her dragon - riding skills could be enhanced in a different way, as she might use her new - found femininity to her advantage while in the air.
First, you need to establish the reason for the transformation. It could be a magical spell gone wrong, or some kind of strange dragon - related phenomenon. Then, focus on how Hiccup adjusts to her new body. She'll have to deal with different physical abilities and limitations. For example, she might be physically not as strong as before, but more agile in some ways.
In a fanfic, Naruto turning into a Pokemon might also lead to some comical situations. Imagine Naruto, now as a Pokemon, trying to communicate with his friends in Konoha. He might have to use Pokemon sounds and gestures at first, causing a lot of confusion among his comrades. But eventually, they figure out a way to understand him, and it becomes a fun adventure for everyone.
One idea could be that Kagome's transformation into a Legendary Pokemon is a result of a strange encounter with a powerful Pokemon artifact in the Pokemon world. Maybe she was exploring an ancient ruin and accidentally activated a spell that merged her with the essence of a Legendary Pokemon, like Mew. This could lead to her having unique powers and abilities that no other trainer has.
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.
In the fanfic, Link could be magically changed into a girl due to a wish made by an innocent character. Link then has to find a way to reverse the transformation while still dealing with the challenges of the world. He might face discrimination or different expectations from others in his new form, which could add depth to the story.
Well, one possible plot could be that Hiccup accidentally drinks a magic potion made by a mischievous wizard. As a girl, he (now she) has to deal with the different reactions of the people in Berk. Some are shocked, some are curious. And she has to learn how to adapt to the new body while still maintaining her heroic spirit, facing the same dragons but in a different physical form.
One idea could be that Hiccup wakes up one day to find himself in the body of a female Night Fury. At first, he's completely confused and tries to figure out how to control this new form. He might struggle with flying at first, but as he gets used to it, he discovers new abilities that come with being a female Night Fury, like a different type of sonic blast. The other dragons in the village are initially startled but then start to accept him in this new form.
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.
One idea could be that Hiccup, after turning into a dragon, has to learn to communicate with his old dragon friends in a new way. Since he now experiences the world as a dragon, he might discover new dragon abilities and secrets that were hidden from him before. Maybe he has to find a way to turn back, but in the process, he helps the dragon world solve a big problem, like dealing with a new and dangerous enemy.
A possible plot could be Issei turning into a girl and having to hide it from his friends at first. This would create a lot of comical situations as he tries to maintain his normal life while dealing with the physical changes. For example, he might struggle with wearing female clothes or using the girls' bathroom without getting caught.