House Targaryen ruled as the Kings of Westeros for nearly 300 years. Their seats were the capital city of King's Landing and the island castle of Dragonstone. Their sigil is a three-headed dragon breathing flames, red on black, and their words are "Fire and Blood."
The Targaryens were not native to Westeros, instead originally hailing from the freehold of Valyria on the eastern continent. Before the Doom of Valyria, the cataclysmic event that destroyed the ancient civilization, the Targaryens departed for the island citadel of Dragonstone off the Westerosi shore, which was at that time the westernmost Valyrian outpost. The title of Maester Thomax's work 'Dragonkin, Being a History of House Targaryen from Exile to Apotheosis, with a Consideration of the Life and Death of Dragons', mentioned in A Feast for Crows, seems to indicate that the Targaryens were exiled from Valyria. The Targaryens abandoned the Valyrian gods and converted to the Andal faith of the Seven Gods, then the predominant religion in Westeros. A century after that cataclysm, Aegon I, styled the Conqueror, began his conquest of mainland Westeros, landing with dragons and an army (at what would later be called King's Landing). Six of the seven kingdoms fell before him.
Uniquely among noble Westerosi families, the Targaryens follow the Valyrian practice of incestuous marriage, wedding brother to sister. The phrase "blood of the dragon" refers to a number of typical Targaryen features: silvery-gold (or platinum) hair and violet eyes. Some Targaryens also have a high tolerance of heat, though they are by no means immune to fire.
The Targaryens are known as dragonlords, and seem to be closer to dragons than other men are. Aegon I introduced dragons to Westeros when he conquered it, and dragons were kept and ridden by the Targaryens until the last one perished in the reign of Aegon III Dragonbane.
Probably due to their incestuous practices, the Targaryens are prone to madness; King Jaehaerys II said that with the birth of a new Targaryen, the gods tossed a coin to decide whether the child would be great or mad.
ALLIED HOUSES: None
ENEMY HOUSES: All Great Houses of Westeros