Oberyn Martell

Prince Oberyn Nymeros Martell, also known as the Red Viper, is a member of House Martell and is the younger brother of Doran Martell, Prince of Dorne. Oberyn has eight bastard daughters called the Sand Snakes, the four youngest of whom are by his current paramour, Ellaria Sand. Prince Oberyn trained at the Citadel in his youth, in order to become a maester. Although he ultimately grew bored and abandoned his studies, he managed to forge several links in a maester's chain, and became well versed in the use of poisons in the process. When he was sixteen, an older nobleman caught Oberyn in bed with his mistress and wife, and challenged Oberyn to a duel to first blood. Oberyn won the duel, and several days later the man died from festering wounds, likely because Oberyn had poisoned his blade. Oberyn also traveled to Essos in his youth. For a time, he served in the mercenary company known as the Second Sons. It is implied that Oberyn fought duels in the infamous fighting pits of Meereen.