Denizens of Niflheim are called the Vorst.
Born on Niflheim an island surrounded by a mountain range, and thick fog that the king of Niflheim can control.
The kings home on a mountain in the middle of Niflheim.
Standard vorst home.
Normal ice dragons on Niflheim the Vorstgan. Shoot out a concentrated beam of ice fire. Can freeze there prey to paralyze or kill with there ice can kill within an hour it. The ice slowly spreads there whole body within the hour. The only one who can stop it is the kings family. Can live off of Niflheim but choose not to because of the better environment they hunt wild boars cows lamb etc. They have a good relationship with the vorst and protect them from foreigners. Occasionally bring food to villagers either to share or have cooked certain dragons prefer cooked meat spoiled right. Can be ordered by the king.
The leader of Niflheim can transform into a dragon but only the leader/king.
Kings name Yuki Yoverson king of the Vorst and Vorstgan. Age 16. Personality cold to most though cares for his people will kill foreigners who didsrupt and harm their kingdom lives his wife and ruffnut. Ice manipulation abilities While human mainly making weapons. Master with the bow, dagger, and the spear.
Lord of ice dragon form/MC
Less beard hair lightning and ice abilities. Can manipulate size not bigger but smaller to the size of a wolf.
Svanna ingolf wife of Yuki Yoverson, queen of Niflheim. age 15 daughter of the second most powerful clan in Niflheim the frost wolf clan. Rides Yuki and met at age 9 timid nature. Does love Yuki but got married early because of the deaths cause by Odins scourge
Eri an orphan taken in by Yuki. Is quiet in nature but likes story's sometimes plays with other kids at the orphanage. Likes to play with Yuki's dragon form when small and ride on his back. Calls Yuki papa and is five years old.
Ruffnut Thorston sister of Tuffnut Thorston. Trickster at heart doesn't get compliments so likes them can be girly but a true tomboy.
Bow and arrow made from ice when the arrow comes in contact with the target it flash freezes then still alive but frozen potentially deadly.
Story
Yuki was born to the king, and queen of Niflheim everyone there lives in bliss they had not lack of food or comfort. The scourge of Odin took the lives of many Vorst including the king and queen. Population went from 180,000 Vorst to 68,000 7,000 being fisherman, 8,000 hunters, 8,000 soldiers, 10,000 farmers, 2,500 metalworkers, 2,500 carpenters, 10,000 elderly, and wives, 10,000 children, 10,000 other. Only barely more than 1/3 of the initial population but even with the plague after Yuki was crowned king at the age of 10 they began to flourish once more. In six years the population grew up to 80,000. Also Niflheim has card games, lots of books, board games, etc for entertainment as to not get bored. Has Public library. Yuki married Svanna at the age of 16.
The dragon riders arrive on Niflheim on lets say in between season 2-3 most likely looking for new dragons, and find a island surrounded by fog and decide to check it all together. Being naive and attempting to tame a Vorstgan they anger a pack of Vorstgan and flee above the mountain range and find the Vorst houses not after Hookfang, and Meatlug are hit with their frost breath. Flying/falling to the ground near one of the villages tell the villagers what happened and ask if there's any way to help there dragons. The villagers laugh at them because they tried to tame a Vorstgan which angers Hiccup a little. They tell them that only the king can help with an injury like that. They ask where he lives and they tell them. As Hiccup and crew go to the kings house but are stopped by some guards and the guards say they will inform the king while the riders try to argue but have no choice but to wait. While the riders are freaking out Yuki, Svanna, and Eri hear the guard explain what's going on. And decide to finish the story they were telling to Eri. Yuki walking with the guard in front with a spear Svanna to his left while holding Eric's hand on his right. The guard introduces them as the king, queen and Princess of Niflheim. While the riders area still freaking out and Ruffnut slightly attracted to the king Yuki just looks at them with cold unfeeling eyes. Who are you he says to them. Mildly startled Hiccup asks could you help our dragons they were attacked by I think the villagers said Vorstgan. Yuki looks at them again and says who are you. Startled once again they finally introduce themselves with Ruffnut starting. After they introduce each other Yuki points to himself then Svanna, and Eri. I am king Yuki this right next to me is my wife Queen Svanna and this he says with a faint smile on his face while looking down is my daughter Eri to which Eri just beams but hides slightly behind Yuki because they are unknown Strangers. The whole Dragon riders were shocked hearing this man in front of them who looks to be about the same age is married and even more so when he mentioned his daughter. After a minute Hiccup coughs to try to forget his lapse in judgement and once again asks for help. Yuki turned his head and decided to ask why did they attack you unless you were bothering them in their territory or attacking the villagers they shouldn't have bothered you so answer carefully. Startled at the not so veiled threat they look a little uncomfortable cause they did intrude on their territory. Hiccup while we were in their territory we just wanted to see if we could tame them or if they were hostile. Yuki looks at them with slight anger and says so you went to an unknown land and attempted to "train" an unknown dragon which happen to belong to me then have the gull to ask me to help you for your own foolishness.
Idk the first half of the story just helps for setting the scene I guess and I didn't know the population of Berk and when I looked it up I made my places populations slightly lower I think.