Brother the asura Madhu. They were together known as Madhukaidabhas. There are two marginally different stories seen in the puranas regarding their birth. As per Devibhagavata Pradhamaskanda, before land was formed, there was only a vast ocean, and only Vishnu floated on it. From his navel, a lotus plant grew and flowered. On it was born Brahma and he sat reciting the vedas. From Vishnu’s earwax were formed two rakshasas called Madhukaidabhas. As per Mahabharata Shantiparva Chapter 348, on the lotus that bloomed, there were two water droplets. One was as tasty as honey and from it was formed Madhu. The other was its opposite and from it was formed Kaidabha.

Madukaidabhas grew up in the ocean and wondered how it was formed. Then, Devi appeared and gave them the knowledge of the Vagbeeja mantra. They chanted the mantra for a thousand years and prayed to her. Devi was pleased and asked them to seek the boons they desired. They desired for control of their own deaths. Devi agreed. From then on, they became arrogant and started hurting other living beings as per Devibhagavata Pradhamaskanda.

They once saw Brahma reciting the four vedas. They stole the vedas and hid in patala. Brahma followed them and they prepared to attack him. Brahma approached Vishnu, who was lying in yoganidra. Vishnu woke up as per Devibhagavata Dashamaskanda. As per Brahma’s request, Vishnu began fighting them. Madhu and Kaidabha alternately fought him, as the other rested. This continued for five thousand years and finally Vishnu started becoming tired. He understood that they had a boon that would prevent him from killing them. Vishnu started praying to Devi, who decreed that Vishnu would not be able to kill them, and would have to trick them. Vishnu told Madhukaidabhas that he was pleased with them and asked them what boon they desired. They laughed and said that they were stronger than him and so it was Vishnu who required a boon from them. Vishnu calmly asked for a boon that would make him the one to kill them. The Madhikaidabhas were shaken and said that he could kill them anywhere except in the ocean. They thought that Vishnu would never be strong enough to kill them anyway. Immediately, Vishnu made his thighs huge and then showed them as land on top of the ocean. In turn, the asuras made themselves a thousand yojanas wide. Vishnu made his thighs twice that size, placed the asuras on them and killed them with the chakra. The fat remains (medas) of the asuras is what became land later on. Thus bhumi is also known as Medini and became unfit for consumption as per Devibhagavata Pradhamaskanda.

The son of Madhukaidabhas was named Dhundhu. He lived beneath the sand in a desert named Ujjalaka. He was finally killed by a king of the Ikshvaku dynasty – Kuvalayashwa. The king then came to be known as Dhundhumara as per Mahabharata Vanaparva Chapter 202. Madukaidabhas were reincarnated as Khara and Atikhara. (see Atikaya)