Daemon Sand

Ser Daemon Sand is a minor character in the fourth season. He is a knight, and serves as squire for Prince Oberyn Martell.

Season 4
Ser Daemon squires for Prince Oberyn Martell during Tyrion Lannister's trial by combat, and coats his master's spear head with deadly manticore venom. He witnesses the Red Viper's death at the hands of Ser Gregor Clegane.

In the books
In the A Song of Ice and Fire novels, Ser Daemon Sand, also known as "The Bastard of Godsgrace", is Ser Ryon Allyrion's natural born son. He serves Prince Oberyn Martell as squire, and received his knighthood from the Red Viper himself. There are also rumors that he is one of Oberyn's lovers, though this is seldom said to his face.

Ser Daemon is close friends with Arianne Martell, daughter and heir of Prince Doran, and took her maidenhead when they were both fourteen. When Prince Doran learned of this he didn't seek to punish Daemon, but refused to allow him to marry his daughter.

He is considered to be one of Dorne's finest swordsmen.

House Allyrion is one of the "salty Dornish" families, those found along the coasts and Greenblood river system who have the most Rhoynar blood, and who generally have olive skin, dark hair, and dark eyes. His brief appearance in Season 4 of the TV series did not resemble this, but as it turns out, in the books themselves he is not described as having classic "salty Dornish" features. Instead, he is said to have sky blue eyes and light sandy brown hair. Daemon is a bastard son, so the simple explanation may be that he takes after his non-Allyrion parent in looks, and this parent was either a "stony Dornishman" from the western mountains, or possibly from somewhere outside of Dorne entirely.