Cole is a spirit turned mostly-human whose form was modeled after a mage who died in the White Spire after starving to death in the dark. The spirit of Compassion was overcome with grief and took Cole's shape so they could help others. Initially, he was confused and killed other mages trapped in the dungeons of the Spire as a "mercy killing" as they were suffering from abuse, neglect, and some were destined to be made Tranquil. He was becoming a demon of despair.
After meeting a mage named Rhys, Cole turned away from his previous behavior and eventually set out to help others once the mage rebellion started. He killed the corrupt Knight-Commander before leaving the Spire. After joining the Inquisition, he does what he can to help around Haven/Skyhold, and gladly follows the Inquisitor to assist the people of Thedas during these uncertain times.
In this verse, he's encouraged to go the more human route, rather than the spirit.