Serma is a priest that watches over children at a local orphanage, and is Idimaria's caretaker.
It is later revealed that he was a convict who was executed for murdering over 40 people. His soul was saved by Elemonia, who struck a deal in which he could live again in exchange for killing some demons. After he was released from the contract, he decided to become a priest. Later on the church leaders tell him they know who he is, but allow him to keep his position in exchange for murdering a young Idimaria (which he doesn't).