Jay is one of the chief aides to the King of the Riverlands. He is acting with the men who first come to Shelling to enlist men for the army before the war, and he is with the King when they capture the three youngest children as they are returning to their camp from Kankredin's ship.
Tanaqui remembers Jay from that first encounter, because he smiled and winked at Robin when she came out with floury arms from her breadmaking to see them all arrive in the village. Hern remembers him because he is the one who announced that Hern was too small to take to war. But Jay doesn't remember them, and the King's party doesn't quite believe the children are not Heathen.
When Tanaqui insists that they have the hearth statues of the Undying, which proves that they are Shelling people, she mentions the fact that The One is still in his fire in the camp, along with his sister, who is ill. The King sends Jay and ten soldiers to escort Hern back to the camp to retrieve the statue and the sister.
After traveling with the King's company upriver for many days, they come to the area around Shelling village, and Tanaqui insists they stop so Robin can get well. Amazingly, the King does so, and by Jay's many visits to their quarters, Tanaqui realizes that Jay is courting Robin, who wants none of him. Jay lost an arm in the wars, and his stump seems to jump about in an alarming way. He is also older than Robin, and very fond of boasting of his many conquests of women.
Eventually, Jay almost kills Tanaqui, in a rage over what he considers thievery and betrayal of his confidences about wanting to marry Robin before the King can. Jay, though cheerful and sometimes helpful, in a self-interested way, turns out not to be a very nice person.