Arnolf Karstark

When Lord Rickard Karstark marches south with Robb Stark and takes his sons with him, Arnolf is left in charge of Karhold. When Stannis Baratheon sends word from Castle Black announcing his arrival and demanding loyalty, Arnolf is the only northern lord who pledges him support. Since Jon Snow has refused to rule Winterfell in Stannis's name, the king considers giving the castle to Arnolf instead.

During the feast Ramsay Bolton holds at the Dreadfort before marching on Moat Cailin, Arnolf and Hother Umber sit beside him without Theon Greyjoy recognizing them. Arnolf later writes to Stannis to let him know the Boltons have left the Dreadfort, leaving behind only fifty men.

At Barrowton, Theon overhears Ramsay and his father, Lord Roose Bolton, saying that Arnolf is plotting something against Stannis; Roose is counting on Arnolf betraying him once the king marches on Winterfell. Alys Karstark — daughter of a now-dead Rickard — flees Karhold seeking shelter at the Wall. There she reveals that Arnolf answered Stannis hoping the Iron Throne, on finding out, would order the execution of Lord Harrion, his captive brother: Harrion's death would make Alys the heir, and Arnolf meant to force her to marry his son Cregan to seize Karhold, all in exchange for a pardon Roose had promised him on the Lannisters' behalf.

Clydas sends a raven, in Jon's name, toward Deepwood Motte, hoping word will reach Stannis. When Cregan tries to get Alys out of Castle Black, Jon has him locked up.

When the king marches on Winterfell, Arnolf joins him with his army at a peasant village: four hundred spearmen, archers by the score, a dozen mounted lancers, and Maester Tybald, carrying a cage full of ravens. Ser Justin Massey doubts such forces are enough to take Winterfell from the Boltons.

Arnolf is a thin old man who leans on a cane to walk, his left shoulder nearly half a foot higher than his right, with a scrawny neck, narrow grey eyes, a few grey hairs above an otherwise bald head, yellowed teeth, and a white beard. Theon Greyjoy calls him "a ruin of a man."