Sweetsister is an island of the Three Sisters in the Bite. It is the seat of House Borrell, who are sworn to the Arryns of the Vale. The town of Sisterton and Breakwater Castle are located on Sweetsister.
A Dance with Dragons
Salladhor Saan loses heart and decides to abandon Stannis Baratheon, sick of waiting for payment from the king. His fleet is off the Three Sisters when this happens. He refuses to take Lord Davos Seaworth to White Harbor but does not throw him overboard as he threatened. Instead, Davos is set ashore on Sweetsister by rowboat.
Davos is caught in the Belly of the Whale trying to buy his way off island, and he is brought before Lord Godric. Rather than turn Davos over to Lord Triston Sunderland, Godric allows him to continue on to White Harbor.
- A Dance with Dragons, Chapter 9, establishes Sisterton on the island Sweetsister, while the Map of the North in the same book shows Sisterton on the central island. However, The Lands of Ice and Fire labels the central island as Littlesister and the easternmost island as Sweetsister.
- A Dance with Dragons, Chapter 9, Davos I.