A blood feud indicated the most serious type of disagreement within the societies of Alagaësia. To declare a blood feud against someone generally indicated that one party intended to kill the other, forcing the other party to either go to great measures for protection, flee, or attempt to kill in return.

Birgit declared a blood feud against Roran for his role in the death of her husband, Quimby. Despite this feud, the two acted together in both ensuring the safety of Carvahall and in Birgit's aiding of Roran's wedding ceremony. Despite this, Roran knew that she was a deadly enemy and had to find a way to deal with her, or pay her price. At the end of Inheritance, Birgit settles her blood feud with Roran by cutting the palm of his hand with her sword.

In Eldest, it was suggested that a quarrel between Thane and Albriech might result in a blood feud, but Roran replied that it was a matter for arbitrators.

The Song of Gerand tells of a man named Gerand who wanted to live a peaceful life, but was forced to kill after a jealous lord declared a blood feud against his family.