Bheem was the second of Pandavas. His mother was Kunti. Who
is the father of Bheem in the Mahabharat is
explained below in the story. She was married to Pandu. But Pandu could not
have sexual union with Kunti because of a curse. Kunti due to her service to
Sage Durvasa had got a boon that she will be able to summon a god and have
children in him. Pandu requested Kunti to make use of the boon. Thus Bhima was
born when Kunti summoned Vayu, the wind god in Hinduism. Vayu blessed her with Bhima.
But as per social custom that was followed at the time of
Mahabharata, Pandu is the father of Bhima.