The joint project of Ocean churning by Devatas and Asuras had been a great success for Devatas. They had received Amrit and obtained immortality. Asuras did not go empty handed either and received many treasures. But Lord Vishnu outwitted them in his avatar as Mohini. He ensured only devatas drank Amrit and became immortal. The Asuras felt cheated and in their rage declared war with the devatas. In the war Devatas killed many Asuras. Devatas were now immortal and thus would not die.
Devatas and Asuras were step brothers. Their father was Rishi Kashyap. Rishi Kashyap’s wife Aditi gave birth to the Devatas and his wife Diti gave birth to the Asuras. Diti, Asura mother was enraged to see her children die at the hands of Devatas. She cried in front of her husband and asked him to give her sons who could defeat the Devatas. The great Rishi Kashyap granted her wish. In time Diti gave birth to two great demons – Hiranyaksh and Hiranyakashyap. Diti raised them with one goal– defeat and embarrass the Devatas. To do so, Hiranyaksh began severe penance to please Lord Brahma. He sat under a tree for many years chanting a mantra. He gave up food and water and never moved from his place under the tree. After many years Lord Brahma appeared and said “Hiranyaksh, I am pleased by your penance. Rise and tell me what you want”. Hiranyaksh bowed to Lord Brahma and asked for immortality. “No Hiranyaksh. All who are born must die. I cannot give you immortality. Ask for something else” replied Lord Brahma. Hiranyaksh then tried to outsmart Lord Brahma. He asked for the following boon – “I should not be killed by humans, Asuras, Devatas, Gods or flesh eating animals”. He thought that if none of these could kill him then he would live forever. Lord Brahma smiled and said “So be it” and disappeared.
Hiranyaksh was filled with new strength. Immediately he gathered his army and started attacking humans. But, he soon grew tired of bullying humans. He wanted to fight someone more powerful and attacked the heavens. The devatas knew they could not defeat Hiranyaksh and so hid from him. As he looked for them he saw the Ocean and decided to challenge Varun – the God of water. Varun tried to hide from him but couldn’t. Frightened by Hiranyaksh attack he accepted defeat. Hiranyaksh then continued searching for Devatas. On his way he met Narad Muni who suggested that Hiranyaksh challenge Lord Vishnu. Hiranyaksh loved the idea. He hated Vishnu for cheating his ancestors during the Amrit distribution. He began searching for Lord Vishnu but could not find him. He then had an idea. He kidnapped Bhu devi (Goddess Earth) and took her to Patal Loka in the Ocean. Bhu Devi prayed to Lord Vishnu to save her. Lord Brahma too meditated upon Lord Vishnu praying for his help. As he meditated a small boar flew out of his nostril. In front of Brahma’s eyes the Boar grew in size and dove into the Ocean to challenge Hiranyaksh. In the beginning Hiranyaksh laughed at the boar for challenging him. As the battle continued he stopped laughing. He realized that his death was near. Hiranyaksh could not be killed by humans, devatas, gods, asuras or flesh eating animals. A boar is a plant eating animal. After a fierce battle Varaha (Boar) killed Hiranyaksh. It then gently lifted Bhu Devi on its tusks and brought her to the Ocean surface. Bhu Devi sang praises of Lord Vishnu in his Varaha form. The Lord assured her that he would always come to protect Dharma (natural order of things). Bhu Devi then used this opportunity to ask the Lord many questions about Creation. That dialogue between Bhu Devi and Varaha is given in the Varaha Purana.