Lord Denys was the titular head of House Darklyn during the reign of King Aerys II Targaryen. He wed Lady Serala of Myr, later known as the "Lace Serpent". Lord Denys rose against the Iron Throne over a taxation issue. When King Aerys II personally led a small force to confront him, Lord Denys had the king taken captive. He held Aerys II within the walls of Duskendale for six months. The Hand of the King, Lord Tywin Lannister, at the head of an army, sat outside the walls of Duskendale, but Lord Denys sent word that he would kill the king at the first sign of an attack. Ser Barristan Selmy rescued Aerys II, however, prompting Lord Denys to open his gates and plead for mercy. He received none, as Aerys II extinguished House Darklyn. Lord Denys was executed along with his wife, brothers, sister, uncles, and cousins.