Sigyn (pronounced roughly "SIG-in") is the wife of Loki and the mother of Vali and Nari.
Sigyn at one point married Loki and had two sons with him, Vali and Narvi. After her husband tricked the blind god Hod into killing Balder, her sons were slain and their entrails used to bind their father. Sigyn stayed by her husband's side holding a goblet to catch the venom that fell on Loki's face. She has not spoken since her sons were killed.
Once the wedding party reaches her husbands prison, she stares blankly at them. She is unfazed by her husband's insults towards her. When the fight breaks out she flees, dropping the goblet and letting the venom drip on his face before Randolph Chase cuts him free.
Sigyn appears behind her husband on the deck of Naglfar. During the flyting she leaves her husband and vanishes amount the crowd.
Sigyn's face is described as being so emaciated, she could have passed as a Draugr. She has leathery skin and bloodred tears streamed down her face.