Thralls of the ironborn may only be obtained by paying the "iron price" (capturing them by raiding) under the Old Way. They are not slaves since they may not be sold and they may not be obtained by paying the "gold price." Unlike the children of slaves, the children of thralls are free if they are born on the Iron Islands, although some ironborn believe the children must be still dedicated to the Drowned God. The children of thralls cannot be taken from their parents until they are at least seven years old, the age when most ironborn begin an apprenticeship or join a crew.
Thralls are used for farming and mining, activities which the ironmen consider unsuitable for free men. Educated thralls are valued by the ironborn as stewards, tutors, and scribes, while craftsmen thralls are also highly regarded. Some ironborn priests are known to sacrifice thralls to the Drowned God by slitting their throats and giving their bodies to the sea.
Thralls were commonly used by the First Men who ruled Westeros prior to the coming of the Andals. For instance, Morgon Banefort, the Hooded King of Banefort, used thralls in his twenty-year war against Loreon I Lannister, King of the Rock. Some of the First Men of the Vale who did not submit to House Arryn after the Battle of the Seven Stars were reduced to thralls.
As time passed, however, south of the Wall thralldom came to be only practiced by the ironborn of the Iron Islands. After Lord Lymond Hightower of Oldtown defended against the ironborn king Theon III Greyjoy, Lymond temporarily used thralldom to punish the captured ironborn through forced labor.
There were at least two thrall rebellions against House Greyiron when they were Kings of the Iron Islands. King Harmund III Hoare was considering outlawing thralldom in the isles when the Shrike began a successful revolt of the priests against his rule. Lord Quellon Greyjoy outlawed thralldom and freed the thralls of the isles, but this was reversed by his son and successor, Balon Greyjoy.
A Clash of Kings
When he returns to Pyke, Theon Greyjoy is attended by thralls in service to House Greyjoy. His father, Lord Balon Greyjoy, intends to conquer the north and make its people thralls and salt wives. During the harrying of the Stony Shore, some of the northern women are taken as thralls.
A Feast for Crows
Qarl the Thrall is a supporter of Euron Greyjoy as King of the Isles and the North. After the taking of the Shields, Lord Captain Victarion Greyjoy is disturbed that Euron intends for captives to be sold into slavery instead of being taken as thralls or salt wives.
The man who owns a boat need never be a thrall, for every captain is a king upon the deck of his own ship.—writings of Hake
There were no slaves in the Iron Islands, only thralls. A thrall was bound to service, but he was not chattel. His children were born free, so long as they were given to the Drowned God. And thralls were never bought nor sold for gold. A man paid the iron price for thralls, or else had none.—thoughts of Victarion Greyjoy
- A Clash of Kings, Chapter 11, Theon I.
- A Clash of Kings, Chapter 41, Tyrion IX.
- A Feast for Crows, Chapter 29, The Reaver.
- The World of Ice & Fire, The Iron Islands.
- A Dance with Dragons, Chapter 62, The Sacrifice.
- The World of Ice & Fire, The Free Cities: Braavos.
- The World of Ice & Fire, The Westerlands.
- The World of Ice & Fire, The Vale.
- The World of Ice & Fire, The Iron Islands: Driftwood Crowns.
- The World of Ice & Fire, The Iron Islands: The Iron Kings.
- The World of Ice & Fire, The Iron Islands: The Black Blood.
- The World of Ice & Fire, The Iron Islands: The Old Way and the New.
- A Feast for Crows, Chapter 11, The Kraken's Daughter.
- A Feast for Crows, Chapter 18, The Iron Captain.
- A Clash of Kings, Chapter 24, Theon II.
- A Clash of Kings, Chapter 37, Theon III.