Sure, a lot of fanfiction writers are attracted to the idea of Toothless and a female Night Fury. In some of these stories, they might be on a quest to save their kind from a new threat. The fanfictions can be a great way to explore different aspects of their relationship that we might not see in the original work, like how they communicate in their own unique ways and support each other through difficult times.
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.
Their interaction could be initially cautious. Since they are both powerful dragons, they would be sizing each other up. But then, they might start to play, chasing each other in the sky.
Another idea is that they team up to protect their territory from humans. They use their stealth and powerful fire blasts to keep the humans at bay. Along the way, they teach each other new skills. For example, the female Night Fury might have a different flying technique that Toothless learns, and in return, he shows her how to better hunt in the ocean.
In the 'Toothless meets a female Night Fury fanfiction', there could be a whole range of things. First off, their first encounter could be filled with a mix of fear and excitement. Toothless might be excited to finally meet another of his kind, but also a bit scared of the unknown. The female Night Fury could be more aggressive at first, seeing Toothless as a potential threat to her territory. But as they get to know each other, they might start to bond. They could fly together, hunting side by side. And who knows, they might even start a new family of Night Furies, which would be a really interesting development for the How to Train Your Dragon universe.
Often, in the fanfiction community, it's hard to tell exactly who the author would be. It could be a young writer, perhaps a teenager, who has a vivid imagination and loves the idea of creating a story around Toothless and a female Night Fury. There are also more experienced fanfiction writers who might take on this concept. They could be people who have been writing fanfictions for years and saw the potential in this particular scenario to create an engaging story.
Some smaller, more specialized fanfiction communities might also have such stories. You could search for them on social media groups dedicated to the How to Train Your Dragon franchise. There, fans often share their own works or recommend good fanfictions that they have read.
His relationship with Toothless would be very different. Toothless might be more protective of him in his new form, as if sensing that Hiccup is more vulnerable as a female Night Fury. And Hiccup would have to communicate with Toothless in new ways, perhaps using more body language that is typical of female Night Furies.
You could start by imagining unique adventures and challenges for the female Night Fury. Maybe she has to protect her territory or form unexpected friendships.
One idea could be that a Night Fury somehow gets transported into the Harry Potter universe. Maybe it crashes into the Forbidden Forest and Harry and his friends discover it. They could try to figure out how to communicate with it and use its abilities to their advantage against the dark forces in Hogwarts.