An archangel, metatron, avatar, or demigod, depending on your perspective. Also known as the Mother of Mercy, among other epithets. Kavreshar's counterpart, sibling, lover. After the Serpent's fall and imprisonment, Emkathon preserved some of its blood in the Phereia and made a bargain with Laeken, a human of the Wolf tribe, to preserve it through their offspring, in exchange for protecting the city. She bore a daughter to him named Katha before she took up her role as guardian of the city of Diablotin. She was confined within a place called the Odyton, deep beneath the Nine Elms church, in the form of a small glowing ball of light. However, she seemingly retained the ability to observe and affect the city and communicate, albeit through unconventional means, with its inhabitants. Seth Argo formed a particular bond with her, and thus the city itself, via the golem Schesutte.
After her release, Emkathon took the time to offer Earric the possibility of redemption, to bless Ilphere and her daughter Cordovera Kizer and all her descendants, to feed the infants Justen Olivier and Mercy Olivier (and thus possibly counterbalance Kavreshar's effects on them in some way), and to offer some words of comfort to Ysabeau. She also presumably met with Phedre to receive the Phereia, although that encounter is not recorded. She was then reunited with Kavreshar at the Black Down, where their combined energy healed the Arch before they disappeared into it, to an unknown destination and purpose.