Similar to to his brother Koios, Iapetos wasn’t as important as his offspring and descendants.
He fathered Atlas, Prometheus, Epimetheus and Menoitios. He got together with one of the Okeanides to create his children. Iapetus was one of the four titans who held down one of the four corners of the cosmos. Iapetos was most likely pillar of the west. This was while Kronos castrated his father Ouranos with his scythe. He was nicknamed the Piercer and was god of mortal life span.