Hiccup would probably be overjoyed. He has such a deep bond with Toothless, and seeing Toothless become a father would be a very special moment for him. He would likely be very involved in helping Toothless raise the babies, teaching them things he has learned from his own experiences with Toothless.
The Vikings in Berk would initially be cautious. Dragons are still somewhat of a mystery to them, and baby dragons might seem even more unpredictable. But as they see how Toothless cares for his babies and how the babies could potentially be beneficial to the village, like helping with fishing or protecting against other threats, they would gradually warm up to them.
The other dragons in the flock might have a mix of reactions. Some of the older, more experienced dragons could be protective as well, seeing the babies as the future of their kind. However, some younger or more mischievous dragons might be a bit jealous at first, especially if Toothless is giving a lot of attention to his babies.
Their babies could have a combination of Toothless's black scales and Stormfly's greenish - blue scales. Maybe they would have Stormfly's long, slender body shape with Toothless's large wings. They might also inherit Toothless's bright blue eyes.
Toothless is known for being intelligent and curious. His babies might inherit this, always getting into little adventures to explore new things. Stormfly is feisty and strong - her babies could be brave and not afraid to stand up for themselves. So in a fanfiction, the Toothless babies might be the ones coming up with the ideas for exploration, while the Stormfly babies are the ones ready to fight any danger that comes their way.
Sakura would be very concerned. She has known Naruto for a long time and has seen his growth. She would probably try to be there for him, using her medical skills to make sure he's physically okay and offering emotional support. For instance, she might sit by his side and talk to him about his feelings, just like she did when they were younger.
Sakura might be initially shocked but then she would be determined to help Naruto find out what's wrong. She could start researching in the hospital's library for any medical or historical records related to such a phenomenon.
The teachers at Hogwarts, like Dumbledore, would be deeply saddened. Dumbledore might see it as a sign that Harry is being influenced by dark forces and would try to guide him back to the right path. Snape would probably be sarcastic and critical, saying that he always knew Harry was not as noble as everyone thought. Other students might be divided. Some of Harry's supporters would be in denial, while others would turn against him quickly.
The other members of Team 7 like Sai would be confused. Sai doesn't fully understand emotions like the others, but he would know that this is a bad situation. He would follow Sasuke and Kakashi's lead in trying to find Naruto and Sakura. Tsunade, as the Hokage, would have to make some tough decisions. She would probably send out search parties while also trying to keep the situation under wraps to prevent panic in the village. The other ninja in Konoha would be on high alert. They would be worried that Naruto's actions could be the start of a larger threat, either from within the village or from outside forces.
Tails would probably be very curious and eager to figure out how to change Sonic back. He might study Sonic's new form scientifically. Knuckles, on the other hand, would be a bit more confused but still stand by Sonic's side. Amy might be initially jealous because she's used to being the main female around Sonic, but then she could become a great friend and help Sonic adjust. Dr. Eggman would likely see this as an opportunity to take advantage of Sonic's confusion in her new form.
Annabeth would be furious. She'd immediately start planning a rescue mission. She might call on all of Percy's friends and allies at Camp Half - Blood. Annabeth would use her strategic mind to figure out where Nico has taken Percy and how to get him back.
His friends like Shikamaru would be deeply affected. Shikamaru, who had always respected Naruto's tenacity, would be at a loss. He might think about all the times Naruto pushed forward despite the odds and feel guilty for not being able to prevent his death. Hinata would be inconsolable. She had deep feelings for Naruto, and his sacrifice would shatter her world. The other ninja from different villages that Naruto had befriended during his journey, like Gaara, would also be in mourning. They would see Naruto's sacrifice as a noble act that inspired them to be better protectors of their own villages and to work towards a more unified ninja world.
Some characters might be very shocked at first. For example, Sandstorm, if she was in a relationship with Firestar before, would be confused and have to re - evaluate her feelings. But others, like Graystripe, might be more accepting and just see it as another change that they have to adapt to. Younger cats in the clan would probably be more curious and excited about this new Firestar.