- "My eldest brother, Rodrik, led a frontal assault on Seagard, a town built to protect the mainland from us. After ferocious fighting beneath the city walls he was slain by Lord Jason Mallister, and his men defeated."
- ―Theon Greyjoy
In the books
In the A Song of Ice and Fire novels, Lord Jason Mallister is a loyal bannerman of House Tully. He has at least one son, named Patrek.
As a young knight, Lord Jason participated in a tourney at Storm's End, where he was defeated by Rhaegar Targaryen. During the early stage of Robert's Rebellion, he attended the wedding of Eddard Stark and Catelyn Tully, giving them lavish gifts. He participated in the Battle of the Trident, slaying three of Rhaegar's bannermen, thus avenging the death of his kinsman Jeffory Mallister, who had been killed under orders of the Mad King.
Lord Jason takes part in the Tourney of the Hand; later, during the War of the Five Kings, he takes part in the Battle of the Whispering Wood and the liberation of Riverrun at the Battle of the Camps. He returns to Seagard after Robb Stark is declared the King in the North.
Lord Jason is one of the seven nobles who are chosen to launch the funeral boat of Hoster Tully. Jason meets Robb on his march north to the Twins. Robb orders him to send two ships into the Neck, one carrying Galbart Glover and the other Maege Mormont, to find Greywater Watch.
In the fourth novel, Jason is forced to surrender Seagard to the Freys, since they threaten to kill his son Patrek, who was taken captive at the Red Wedding. Currently he and his son are imprisoned in Seagard.
|Lord:||Lord Jason Mallister||Heir:|
|Title(s):||Lord of Seagard|
|Current members:||Ser Denys Mallister|
|Deceased members:||Ser Jaremy Mallister · Jeffory Mallister|