Vatapi

A sage called Khaga once did severe penance to please Vishnu. He got what he wanted and returned to the mountain Rishyamukha. On the mountain lived a king called Rishya with his wife, Roopavati. The king died childless. The queen was stricken with grief. She was crying in the forest when her cries were heard by Garuda. He took the form of a human and seeing the queen was in love with her. He asked her who she was. She said she and her husband had come to the forest to pray for a child and in the process the king had died and she was now all alone.
Garuda said he would have a child with her. The queen asked for  hundred children. Garuda lived with her for twelve years. The king Rishya had another wife, Sushila. When she heard about this, she too begged for a child.
Soon both queens were pregnant and they gave birth to eggs. Sushila gave birth to twins - the eldest was blind and called Andhaka and the younger was called Jatayu. The other queen gave birth to a son called Kubala and ninety nine others. Kubala was made the king of birds.
Once the nagas attacked and fought Kubala. Kubala and his ninety nine brothers were killed in the fight.
Andhaka seeing this took refuge with the Nagas. The Nagas made him the king.
When Garuda came to know this he began killing the Nagas and was stopped by Brahma.
Soon Jatayu, the peaceful one had two sons, Sukha and Sarana. Andhaka had thousand sons, the eldest of whom was called Vatapi.
Vatapi made friends with the Nagas. Seeing this Sukha and Sarana prayed to Shiva and got boons. They realized that Vatapi would bring an end to their clan. So with the boons, they and fought and killed Vatapi.

This is how Dhritarashtra is acting and he will then go the way of Vatapi.

Ilvala and Vatapi

Pandavas reached the forest of Naimasha and from there, having bathed in the river Gomati they went towards Prayag where Yamuna meets Ganga. There, they reached the ashrama of the sage Agastya. Lomesh said to the Pandavas, this is where Agastya killed demons and setup his abode. Listen while I tell you about Agastya.

One day, the sage saw his deceased ancestors hanging in a pit, upside down. Agastya asked them why they were in the pit, and that too upside down.

The ancestors  said they were in this position as he, Agastya, was a celibate and did not have any children.

Agastya decided to get married, but to whom? After much thinking, he decided that the princess of Vidharba, Lopamudra, was the person who would be his wife.

In Vidharba, the king was wondering, who would be the fit husband for his daughter. Agastya then came there. The king asked him for the reason of his visit. The sage said he wanted Lopamudra as his wife. The king did not know what to say. He went to his queen and asked for her advice. Lopamudra, hearing this, went to her parents and said Do not grieve for me. Give my hand to Agastya.

The king agreed and with all rituals, he gave away Lopamudra to Agastya. Agastya asked Lopamudra to discard her royal clothes and jewels and take the garb of an sage's wife. Lopamudra immediately did so.

Agastya took Lopamudra with him and lived on the banks of Ganges. One day he said to his wife, I married you to get children. What is the use of our marriage, if we do not have any children.

Lopamudra, with folded hands, said My Lord, As per the rules of nature, physical intimacy is needed to have children. If you want to arouse passion, then give me royal clothes and jewels. Wearing those, my beauty will arouse you and then a child could be born.

Agastya then approached a king called Shutarva and asked for wealth. The king said there was little he could spare. He said there were two demons Ilvala and Vatapi. They were cunning demons who were well versed in magic. Vatapi took the form of a goat and the same was fed to sages. Then Ilvala would call out to Vatapi, and Vatapi would come out tearing the stomach of the sages and the people who had eaten the meat thus killing those people, thereby robbing them.

Agastya decided to teach them a lesson. He went alone to the house of Ilvala. When Ilvala asked him the reason for the visit, the sage he was tired and hungry. Ilvala said he would feed him lamb and asked him to wait. Ilvala had Vatapi take the form of a lamb, which was offered to Agastya. The sage said he wanted to have the whole lamb with skin and bones, leaving nothing out. The wishes of the sage was complied with.  The sage ate up everything.

Ilvala then started calling out to Vatapi., Agastya smiled and said Vatapi had been digested and would never come out. Ilvala, bowing down to the sage, asked what he could do. The sage said Give up violence. Give me all the wealth you have accumulated.

Ilvala brought all the wealth out.

The sage brought the wealth over to his wife. Seeing his wife decked up, the sage's passion was aroused. The sage asked what she wanted, and Lopamudra said she wanted only one son.

Soon a son was born to them.