Summer's father is a former hedge knight from the Westerlands named Ser Prentiss the Valiant, her mother a beautiful Dornish whore. She was born on a ship as her mother made her way across the Narrow Sea to seek her fortunes in Essos, living in Braavos and Lys.
Much of her time in Braavos as a child was spent learning to waterdance from the young bravos she befriended, and eventually from a master. She explored, eavesdropped, discovered secrets, frequented places she did not belong, and picked pockets. In time her father discovered he had a daughter, and when Summer was fourteen her mother sent her to Westeros to live with him. Ser Prentiss the Valiant had by then earned a small keep in the peaceful lands of the Reach for defending a lord's heir from highwaymen. There he gave Summer the name Steelsong when he saw her spar with and defeat a fellow knight.
Summer grew from a dirty stringy child to a long, lithe, lovely young woman of seven-and-ten. She has long waves of sunlit golden hair, eyes as green as summer grass, and her mother's caramel skin. She reads voraciously and has taught herself various languages from the books in her father's library. She is intelligent, charismatic, brave, mercurial, easily bored, and often reckless.
Activities
Summer swore herself to Lord Martyn Dayne of Starfall, and then formed part of Danae Targaryen's personal guard on her way to the Wall and to Essos. Summer saved the lives of both Danae and Grand Maester Orin Baratheon in Valyria, and having provided true and loyal service is now the sworn sword and trusted friend of the queen.