Hanuman is the son of Vayu, the wind-god; and Bheema is the son of Kunti, born by the grace of Vayu. Thus the two can be considered brothers. Hanuman is described as a Chiranjivi - an immortal. This explains how the meeting between the two was possible, though Bheema was born many centuries later. The episode also emphasises the feminine intuition of Draupadi who unerringly chose Bheema for a risky and romantic errand.