Yayati
Yayati (Sanskrit: ययाति) was a Puranic king and the son of King Nahusha and his wife Viraja. He was one of the ancestors of Pandavas. He had five brothers: Yati, Samyati, Ayati, Viyati and Kriti. He had two wives, Devayani and Sharmishtha. Devayani was the daughter of Shukracharya, the priest of Asuras (the demons). Sharmishtha was the daughter of the demons king Vrishparva. Sharmishtha was a friend and later a maid of Devayani. After hearing of his relationship with second wife Sharmishtha from Devayani, her father, sage Shukracharya, cursed Yayati to old age in the prime of life, but later allowed him to exchange it with his son, Puru. His story finds mention in the Mahabharata-Adi Parva and also Bhagavata Purana.
The story
The story of Yayati comes in the Book Nine, 19th Chapter of Bhagavata Purana.
Yayati's father, Nahusha, was cursed by the sages to be a python as punishment for his arrogance. Yayati's elder brother, Yati, was initially given the kingdom, but the latter refused and instead became an ascetic. Yayati became the king and conquered the world. He appointed his four younger brothers to rule the cardinal directions of the world.