Hiccup's friends would be extremely worried. Astrid, being Hiccup's closest friend and love interest, would probably be the first to take action. She would gather the other riders and start planning a rescue mission right away. Snotlout might initially be a bit hesitant, but the thought of losing Hiccup would push him to join in. Fishlegs would use his knowledge of dragons to figure out where Drago might be hiding Hiccup.
If the grandfather is very warm and accepting, Shikaneji would feel relieved and happy. They might open up more about their relationship and their dreams. Nejire could start chatting excitedly about their future together, and Shinsou would relax and join in the conversation more. However, if the grandfather is not so friendly, they would be disappointed and perhaps a bit defensive.
Well, he might be initially shocked. He could stand there for a moment, his eyes wide open, trying to process the news. Then, he would probably break into a big smile and hug Astrid tightly, whispering words of joy and excitement.
Well, you could have Hiccup learn some self-defense skills to protect himself. Or maybe he could confide in a trusted adult who helps him deal with the bullies. Another option is for Hiccup to use his intelligence and creativity to outsmart the bullies.
Astrid might initially be in shock. She could just stand there, frozen, unable to believe that Hiccup is really gone. Her eyes wide open and her body trembling as she tries to process what has just happened.
Stoick would be quite surprised and a bit worried. As a father, he'd take on the responsibility of caring for his baby son. He might be a bit clumsy at first, not used to dealing with a baby again. The other Vikings would have mixed reactions. Some might find it funny, while others would be more concerned about how to reverse the situation and get their leader back to normal.
Their friends are likely overjoyed at first. Fishlegs might be a bit of a nervous wreck, constantly worrying about Astrid's health and the well - being of the baby. He'd probably be reading every book he can find on dragon - rider pregnancies (if that's a thing in their world). Snotlout would probably make a bunch of inappropriate jokes at first, but deep down he's also excited. Ruffnut and Tuffnut would be their usual chaotic selves, but also show their support in their own unique ways, like bringing strange gifts they think the baby would like.
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.