In the context of the dragon community, Hiccup as a female Night Fury would have to navigate new relationships. Female Night Furies may have their own hierarchies and social norms. He would be interacting with male Night Furies in a different way, perhaps being courted by some. This would be a whole new experience for Hiccup, and he would have to use his wits to handle these situations while still trying to figure out how to reverse his transformation and return to his human form.
With the other Vikings, they would be extremely shocked at first. Some might be scared, while others would be curious. His father, Stoick, would have a hard time accepting this change at first. But over time, as Hiccup still shows his intelligence and courage in his new form, they would start to see him as the same person on the inside. His relationship with Astrid would also change. Astrid would have to adjust to seeing Hiccup as a female dragon, and there could be some interesting dynamics as she tries to figure out how to interact with him.
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.