Iselle dy Chalion is the daughter of Ias dy Chalion and Ista dy Baocia, Ias's second marriage. She is the half-sister to Orico, Ias's oldest child, and has a younger brother Teidez.
Iselle has a generous mouth, hair in ringlets neither blond nor red, pale skin, and heavy-lidded eyes. She is shorter than her companion Betriz dy Ferrej. Iselle turns sixteen 6 weeks after the opening of The Curse of Chalion, at the midpoint of spring. Her tutor Cazaril tells Ista she is quick at arithmetic and geometry, and "persistent" at Darthacan.