Hanuman as a child was very mischievous. His potent energies were becoming active and that made him a ball of fire. Full of energy and enthusiasm! There is a story about how Hanuman meddled with the Surya Dev (Sun). Here it goes:
One morning, young Hanuman saw the sun rising and thought it was a great yellow ball. He decided to hold it and to play with it. Indra, the king of gods, was watchful of how Hanuman leapt in the sky to get the “ball”. In order to stop Hanuman, Indra threw his weapon, the Vajra (thunderbolt) at the child. Hanuman fell to earth, wounded.
As young Hanuman fell to ground, his father Vayu dev instantly got the news. The enraged father decided to go on a strike until the one who hurt his child was punished. Due to Vayu’s strike, the earth had become miserable within no time. There was no gentle cooling breeze when the sun blazed down. No power to move the rain-bearing clouds and after a point, both humans and animals couldn’t breathe.
The gods knew they had to placate Vayu. So, they offered the baby a multitude of boons. Brahma said that no weapon would ever hurt Hanuman and that he would be able to change his form at will and travel wherever he chose. Indra’s boon was that the Vajra would no longer hurt the child and that his body would be stronger than the weapon. Varuna, the god of the ocean, offered him protection from water.
Agni, the god of fire, blessed him with immunity to fire. Surya, the sun god, gave him the power to change the size of his body. Yama blessed him with good health and immortality. Vishwakarma, the divine architect, offered a boon that Hanuman would be safe from all objects of his creation.
With all these boons, Hanuman became a great warrior who played a crucial role in the Ramayana.