Driftmark is a large island just west of Dragonstone. The Velaryons are of the ancient blood of Valyria and have three times provided brides for Targaryen princes. Their motto is, “The Old, the True, the Brave.” The lords of the house, of which the current one is Monford Velaryon, style themselves as Lords of the Tides and Masters of Driftmark. Lord Monford has a six-year-old son, Monterys. Aurane, the Bastard of Driftmark, is of unknown relation to Lord Monford although half-sibling seems most probable.
Information about House Velaryon that reveals spoilers from the books.