Daemion Velaryon was a member of House Velaryon during the reign of kings Viserys I, Aegon II and Aegon III Targaryen. He was a son of Ser Vaemond Velaryon and his lady wife, and had a brother, Daeron Velaryon.
In 126 AC, after the death of his father at the hands of Prince Daemon Targaryen, Daeron sailed to King's Landing with his mother, his brother Daeron, and his father's five cousins to seek justice from King Viserys I Targaryen and put forward their claims on Driftmark.
In 132 AC, following the death of Corlys Velaryon, Daemion and his brother Daeron contested the claim of Alyn Velaryon as Lord of the Tides and put forth their own claims before the council of regents in King's Landing. When the Hand of the King, Ser Tyland Lannister, and the regents ruled against them, they chose to accept the decision and be reconciled with Lord Alyn, who rewarded them with lands on Driftmark on the condition that they contribute ships to his fleet.