Aruna and Garuda are the sons of Vedic sage Kashyapa and his wife Vinata, daughter of Prajapati Daksha.

[4] Having cursed his mother, Aruna rose to the skies, and was bestowed the position of charioteer to Surya by his father, Prajapati Kasyapa.

Then, the creator Brahma asked Aruna to become the charioteer of Surya, to shield all living beings from his terrible heat.

There is a legend in the Mahabharata that Surya once offered Aruna and his divine chariot to his son Karna which he denied as he didn't want to rely on others to win the war, especially against Arjuna whom he acknowledged as a capable rival.

[7] Another legend, generally told in Indian folk tales linked to the Ramayana, states that Aruna, once became a woman named Aruni and entered an assembly of Apsara (celestial nymphs), where no man except Indra (the king of heaven) was allowed.