Well, in Finland, Joulupukki, which is their version of Santa Claus, is a central character in their Christmas stories. He travels around bringing gifts to children on his sleigh, often pulled by reindeer.
One Nordic Christmas story is about the Yule Lads in Iceland. These are 13 mischievous characters who visit children in the 13 nights before Christmas. They leave small gifts or sometimes play tricks, like stealing sausages if children have been naughty.
The main character is often Fenrir, the huge and powerful wolf. He was a key figure in Norse mythology related to wolf monsters.
Typically, the wolf would be one of the main characters. There might also be humans who interact with the wolf, such as hunters or shepherds.
I'm not sure specifically as I haven't read this exact 'the bat novel'. But in Nordic crime fiction, there are often detectives or investigators as main characters.
The Julenisse is a main character. It's a Norwegian version of Santa Claus, bringing presents to children at Christmas.
One of the main characters is Father Frost. He is a key figure in Russian Christmas, much like Santa Claus in other cultures. He is often depicted as an old man with a long white beard, wearing a thick fur - lined coat, and he brings gifts to children.
The Three Kings are very prominent characters. Melchior, Caspar, and Balthazar are the Wise Men who travel from afar to bring gifts to Jesus. Their journey and arrival are celebrated with much fanfare in Spain. And of course, there are angels who play a role in announcing the birth of Jesus in many Spanish Christmas stories.
Obviously, Jenny is a main character. There may also be her family members like her parents and siblings. And perhaps some friends who join her in the Christmas celebrations.
Nordic children's stories often reflect the close relationship with nature in Nordic culture. For instance, animals like reindeer, wolves, and bears are common characters, which shows how important nature is in their daily lives.
In the Nordic story, the Little Mermaid is often very wild. She has a connection to the power of the sea. For example, she can control the waves to some extent.