When they were young, both decided to perform penance to get special powers to establish the rule of Danavas in the universe.
Rambha and Karambha meditated upon Mālavaṭa Yakṣa, the former seated at the centre of the five fires and the latter standing in the water of a lake.
When he was about to do so, Agni appeared and told him that suicide was worse than killing others, denouncing it as a great sin, and promised to grant him whatever he desired.
Accordingly, Rambha requested Agni for a son more effulgent than the latter, who would conquer the Three Worlds and would not be defeated even by the Devas (Hinduism) and the Asuras.
When Kaushiki was sent to crush the growing power of these two demon brothers, she had to face the stiffest opposition from Raktabīja.