**UNVERIFIED PERSONAL GNOSIS WARNING**
Loki's sons by Sigyn are Narfi and Vali. In the old stories, as part of Loki's punishment (either for insulting the Aesir at Ageir's feast or for his role in Baldur's death, the lore is unclear on this) Vali is turned into a wolf that tears out the throat of Narfi. Loki is then bound with the entrails of his slain son in a cave with a snake placed over his head to drip venom into his eyes until Ragnarok. He is attended by his wife Sigyn.
Context setting with respect to the lore, let's launch off onto a tangent. Many people envision Narfi and Vali as young men. Some even depicting them as children. What is forgotten is that Vali was a grown man with a wife and a child of his own. And that his child was grown when this took place. It stands to reason that Narfi was also grown. I propose that what people are being shown is not how the attack happened but how it was viewed by Loki.
As a parent myself, I know that I will always look at my children and in some respect continue to see them as small, fragile little babes. I know that I will still have that maternal feeling of protectiveness long after they have grown and have families of their own. I believe that Loki looked at his sons and saw them again as children. It is also my belief that Vali's transformation into a wolf was akin to a death as well. Imagine, if you would, the intelligence of a man trapped in something that could not communicate or act as a man.
Loki's told me that their deaths was weirgeld for his role in Baldur's death. He speaks of the events (the death of Baldur, the death of Hod, and his own punishment by the Aesir) with great sorrow. At times, he expresses anger. At times he is quiet and simply mournful, almost withdrawn even. It is a tragedy that Loki has expressed deep, deep sorrow that it was necessary for the fate of the nine worlds.
It is my hope that Narfi and Vali can come to be known in their own rights. The beauty of the world is that the past, present, and future are all interwoven. It is something that has, is, and will happen all at the same time.
Hail Narfi and Vali, Loki's youngest sons.