Illvin dy Arbanos is a Chalionese nobleman who serves as master of horse and spy for his half brother Arhys dy Lutez. He is the bastard son of Ser dy Arbanos, the late castle-warder of Porifors, who was half Roknari, and the Lady of Porifors who was the second wife of Arvol dy Lutez. Illvin's father acknowledged him after his mother's death. He was dedicated to the Bastard's Order in his youth but did not develop a calling. He did not inherit much from his father.
Prior to Paladin of Souls, a demon ridden by Cattilara, Arhys's wife, steals soul-stuff from Illvin to keep Arhys's soul in his body after Arhys is killed. This leaves Illvin in a coma-like state except for brief waking periods. Ista deduces the arrangement and forces Cattilara to share her soul-stuff as well so that Illvin can defend Porifors against the besieging Roknari. Ista and Illvin become lovers; Illvin becomes Ista's seneschal at the conclusion of Paladin of Souls.
Illvin has a high forehead, frosted dark long hair worn in the Roknari style, and dark eyes. He is about 39 years old and is two years younger than Arhys. He speaks Roknari fluently.