His mother died while giving birth to Amari. She had gotten locked in "The Temple of the Faithful" over night. She was found dead in the morning with Amari wrapped up and protected at her side. Given life when and where the dead roam, he was afflected with the wasting disease.
Amari's father, despising him for his disease and the death of his mother, gave him to the church of Pharasma to deal with. After a couple years at the church, it became apparent Amari's disease wasn't contagious or curable and that he had innate abilities to heal. At the age of 7 the begun sending him with traveling priests. Amari came up missing after a trip to Korvosa. Kidnapped by Gaedren Lamm, he was tortured and made to heal others so they could be tortured more. After a year he was able to escape back to Osirion and the church.
Now his life mission is to find a cure for his affliction or appease the gods enough they will release him from it.