Hyperion is the Titan of light and the father of Eos, Helios and Selene by Theia, the Titaness of sight and enlightenment. One of the twelve original Titans, Hyperion was imprisoned in Tartarus after their war against the Olympians.
Hyperion was born to Gaea and Ouranos, the earth and the sky. When Cronos was going to dethrone his father, Hyperion was one of the four Titans that held the sky still, making sure that it wouldn't fall. The reason why he is the Lord of the East is because he was responsible for that part of the sky, hence why the sun always rises from the east. He later took his sister, Theia, as his wife and fathered the dawn, moon, and sun gods by her. Hyperion fought for Cronos during their war against the Olympians led by Zeus and was cast, along with many of the Titans, into Tartarus after their defeat.