Loved the story but it felt short and left more questions than answers.
So, I think it was Konig who mentioned the possibility of the whispers being separate from Jormag? Or somebody else. I believe this to be true.
There is a noted difference in the three cases we have of Jormag speaking (trailer, to the commander, and to Asgeir in his book) and the way the whispers act. I'm wondering if the Whispers are a Svanir related cause, using the mentioned "corrupted raven magic" and/or the type of curse that causes boneskinners to be created. The whispers are malicious, causing people to wander into the snow and freeze to death (Not become icebrood, just die), or possible to the Svanir rituals where they are tearing spirits apart to create the aberrants. The whispers cause the investigator to ditch all her gathered evidence and start completely from stratch. They try to turn the commander against Braham "Doesn't he look tired?" And make Braham doubt himself and give into despair.
So what if the whispers are Svanir caused to tear apart the defenders?
I'm interested in this split of "Jormag's wants" and "The Svanir destroying all they deem unworthy" will eventually come to a head against each other. The Svanir clearly follow Jormag's will, but they destroy all their opposition (unless Jormag directly demands specific individuals kept alive apparently), where Jormag wants everybody to be convinced to join.