- "It wasn't for murder the gods cursed the Rat Cook, or for serving the King's son in a pie... he killed a guest beneath his roof... that's something the gods can't forgive."
- ―Bran Stark
The Rat Cook is the subject of legends and myths in the Seven Kingdoms.
According to this particular legend, a King once paid a visit to the Nightfort, then the chief castle on the Wall. Due to some offense by the king, (Bran Stark said he couldn't remember the exact reason when he recounts the tale) the cook killed the king's son and served his flesh in a pie to the unknowing king. The king enjoyed the pie so much he asked for a second helping.
The gods cursed the cook by turning him into a fat, white rat which could only survive by feasting on its own young. He was condemned to run the halls of the Nightfort, eating his own offspring. The gods were not offended by the murder, nor even by cooking the son and feeding him to his own father, for a man has a right to vengeance. What the gods could not forgive and cursed the cook for was that he broke the laws of hospitality and protection, which are held to be sacred above all others.
Although not mentioned again, this story presumably serves as a model to Bran's sister Arya when she avenges the deaths of their mother, brother, and pregnant sister-in-law by killing Walder Frey, who lured the murdered Starks into a false sense of security by officially extending them guest right. First, she kills his sons, Black Walder and Lothar, who respectively murdered her mother and sister-in-law, and carves them into pies that she serves to their father, disguised as a serving girl. When Walder voices his frustration with his sons for their tardiness, Arya sardonically reveals to his horror that he just consumed their flesh before slitting his throat.
In the books
The story is much the same in the A Song of Ice and Fire novels, except that the king in the story is identified as an Andal king. It is extremely well-known in the North and there is even a popular song about it. The song is used to represent the repercussions to those who violate the sacred guest right.
In the fifth novel, Lord Wyman Manderly brings three huge pies to the wedding of Ramsay and "Arya Stark", serves them to the Boltons and the prominent Frey guests, then requests Abel the bard to play the song about the Rat Cook. Perhaps it is a clue that those pies are, as speculated by fans, made of the three Freys who attended Lord Manderly's court at the White Harbor, and disappeared without a trace on their way to Winterfell - a payback for the death of Lord Manderly's son at the Red Wedding.
George R.R. Martin may have drawn inspiration for the Rat Cook from the Greek myth about the curse of the House of Atreus. The two brothers Atreus and Thyestes were feuding over the kingship, and Atreus discovered that Thyestes was having an affair with his own wife Aerope. Atreus exacted revenge by inviting Thyestes to dinner at his home, then secretly killed Thyestes' sons, cooked their meat, and served it to the unknowing Thyestes. After he had finished consuming his own issue, Atreus revealed to Thyestes what he had done and taunted him with the severed heads and hands of his sons. This is the source of modern phrase "Thyestean Feast", one at which human flesh is served.