Prior to becoming a mercenary, Proktos was a priest from a cult of Artemis. At some point, bandits destroyed the temple he served in, leaving Proktos as the sole survivor. He soon joined a lunar cult and pledged to eliminate those who went against and sought to harm his beloved goddess.
Around 422 BCE, Proktos was hired by the magi of the Order of the Storm Phila to hunt down the misthios Kassandra. He and another mercenary Kephalon the Thinker were sent to patrol Boura located southwest of Patrai. Later, Proktos and Kephalon were eliminated by Kassandra herself.