Narfi is one of Loki’s sons and twin brother to Vali. In Norse mythology, Vali is turned into a wolf and forced to attack and kill his brother, after which Loki is bound under a serpent with his entrails. (I know. Pretty disturbing, right?)
In Ice Warriors, Narfi is trapped as a spirit in the ice palace, along with his chained father and his mother. Mainly skilled as a warrior, Narfi also has some magic ability due to his father being a powerful mage.
Personality-wise, Narfi is honourable and noble. He does have a mischievous streak, but there’s nothing cruel in it. He was originally meant to be a main character in book one, but his part has fallen back a bit… though he still has an important role to play.
You can probably tell, due to the different styles, but I was fortunate to get three separate artists who were able to show different portrayals of Narfi. Personally, I think they’re all especially cool and each one demonstrates a particular aspect to his character. In mythology and in the series, he’s probably quite a tragic character.