Season 1 Ep. 2 - Prelude 2
Ryan was a children's author with poor health. He dreamed of fantastical worlds where fairies and other creatures resided and recorded them in the form of picture books. At one stage during his treatment, he met Dr. Jin Young-sam, who was a fan of his works. Young-sam promised to help him survive and recover from his illness.
As time passed, Ryan lost faith in Young-sam and his hospital treatment. His despair led him to follow Ares and become a Deman, subsequently killing all of the doctors around him. Afterwards, he continued to stay by Ares' side as one of his closest subordinates.