Born to the now-fallen Chelaxian noble house of Spiros, Sotiria was the first child to be born a tiefling, the second being her younger sister Chrysanthe after many generations of fiend-blooded Sorcerers.
This taint was the result of the family's past dealings with fiends, as their family was not just known for skilled wizards and alchemists, but also for the dangerous associations they had to the Blackfire Adepts, which once led to a thanadaemon tainting their lineage. Though born into one of the most hated "castes" in Cheliax, the two girls were accepted by their family and quickly had their tainted blood hidden with a mix of illusion magic and well-placed bribes by their parents.
However, their peaceful times came to an abrupt end just as Sotiria had turned 24, as her family was found guilty of heresy and chased out of Cheliax by agents of House Thrune. This led to the separation of the sisters and to the death of their parents as Sotiria escaped to Ustalav while Chrysanthe arrived at Varisia via Nidal. Finding refuge in the haunted nation thanks to an old friend of her father, Sotiria later became a priestess of Pharasma as she realized her soul had a larger stain on it from her fiendish blood than she had originally thought. During the 4 years she has lived in Ustalav, Sotiria had grown an affinity for the arts of necromancy and befriended an estranged dhampir Inquisitor of the Pharasmin church known only as Dampé, with whom she has now taken to hunting down the undead that infest the area.