Evrion's father, Maferath, was an Alamarri chiefrain, commanding the biggest and most powerful Alamarri tribe. His wife, Andraste was too ill to bear children, and thus in order to have an heir, he needed to have one with a concubine. He sired three boys with a woman named Gilivhan. After the concubine's death, Evrion and his brothers were adopted by Andraste.
After his step mother's death, Evrion returned to the Alamarri lands with his father. Maferath gave his sons the task helping him strengthen the lands under the Alamarri rule. Maferath had entrusted his middle child with looking after the lands north of his own, which would later become the modern Free Marches.
Evrion is described as the most pious of Andraste's sons; he was more concerned with spreading her word than with power, and did just that for the decade before her untimely death. When Maferath's betrayal became known to him, he disowned his father and dispersed his holdings among his people.
Unlike the lands controlled by his other two brothers, the ones under his command never developed into full-fledged nations. Instead, each of the towns and cities under his former command elected a separate ruler and would become independent city-states.
Years later the area came to be known as Free Marches. Despite multiple attempts at conquering it, no one, not even the mighty Tevinter nor Orlais ever managed to fully control these lands.
Two of his children claimed to be Maferath's descendants, and were in turn killed for it. Whilst it is possible some of Evrion's descendants yet live, it would be impossible to prove as all of them fell into obscurity.