He is a large man with plentiful, shaggy brown hair. Even in the cooling fall days he wears only a pair of crude breeches held up with a length of rope. He is friendly and takes a liking to the Unexpectables almost immediately.
It was discovered upon returning to the material plane from the Realm of Discord that on nights with a full moon, Halfdan "Becomes one with Bear" by losing control of his werebear form and going loose with no control. After getting beaten up by the Unexpectables and Euphoria, he returned to his true form, leading them back to the settlement. After that, he leaped back into the forest to finish off the time the full moon was up.
Halfdan gets along well with Bjornson and hunts with him. He is especially interested in Bjornson's sister, Frelda, but she has rebuffed his advances.
Halfdan has openly expressed romantic interest in Frelda, but she does not feel nearly as warmly towards him as he does her. There is a reason why, but Halfdan keeps it secret from everybody but Panic. These unrequited feelings lead to strenuous heartache for Halfdan. He has known her since childhood and also knows that she is haunted by the memory of seeing her family killed in front of her by a blighted bear. It was revealed that Frelda was wary of Halfdan because he is a werebear.
During their hunting trip, Halfdan bonds with Panic over shared experiences of being an outsider even among family. He encouraged Panic to share his feelings, and in return, shared a secret with Panic.
Halfdan guided Task and the rest of the party to find a bear for Task to hunt for his Man Trial.
Halfdan sadly compared Greckles' stealth tactics to Frelda's tendency to avoid him. Halfdan then clumisly tried to explain that he isn't attracted to Greckles, which led to some teasing from the rogue.
- There is evidence he is something more than just a really hairy bear of a man during certain times of the month.