Seo Kyung-Hee was born to Seo Young-Chul, a retired general in the Korean war, and Circe. For the first five years of her life she often had small outbursts of using her powers however it wasn't until her father and her took a "holiday" to the United States, specifically The French Quarter of New Orleans, that she had a notable use of her powers. It happened when her father had left her at a daycare centre whilst he made deals so he and his daughter could move to America. In the daycare Kyung-Hee had been taken to the bathroom by a member of a secret witch coven when she showed her powers. Amazed by it, the witch coven member snatched the child and took her back to the coven where she adopted the name Mary. From the elders she was indoctrinated to believe she was a witch rather than a demigod.
After growing up in the coven for twenty years, a 26-year-old Mary broke away from the coven and moved back to South Korea to start a family, going by her old Korean name. After a few months after arriving in Seoul, Kyung-Hee met Boreas who revealed the truth to her. He told her of the Greek world and who her mother was and who he was. At first she didn't believe him due to his indoctrination, but after a while she saw the truth and was shocked. The two dated on and off for a few months before Kyung-Hee was left pregnant. Nine months later she gave birth to a son who she named Sang-Hyuk on the 19th March 1995.
Kyung-Hee and Sang-Hyuk lived in Seoul for five years, before returning to The French Quarter. This time, however, Kyung-Hee didn't move back in with the coven, yet stayed affiliated with them which allowed her to speak to old friends and Sang-Hyuk to create friends of his own among the coven's young. Seeing how the coven's way of raising children was effective, Kyung-Hee made sure Sang-Hyuk was home-schooled and taught him how to use a small sword. What she did differently, however, was raise him to know the truth but telling him to never speak the words he was told in the coven as the consequences were too high to risk.
Due to the family's home being close to the coven full of demigods, monsters would often pass their house and smell the demigod family, attacking them in which Kyung-Hee would always defend them from. By the age of 11, Sang-Hyuk had mastered how to form ice to throw at the monsters.
When he was 13, he met a girl from the coven, Kenzie Chai and the two became fast friends. In retaliation of the nickname 'Hyukkie' that she had given him, Sang-Hyuk named her 'Minnie' from her Korean name of Min-Seo. Around the same time, his mother had bought an apartment in Seoul where the two lived in occasionally. Before he left, Sang-Hyuk told Kenzie what the coven really was about, regurgitating what his mother had told him. He moved away to Korea for three months before returning and meeting up with Kenzie again. His first monster attack happened on his way back to the place he had met Kenzie for the first time. The monster was a harpy and he managed to bring it down with ease, shooting ice at it before hacking it with his celestial bronze dagger.
Sang-Hyuk and Kenzie met at the same place since he was 14 right up to 18. Throughout this time Sang-Hyuk experienced many attacks, all of which he defeated with ease due to his skills and powers become increasingly powerful; enough of that to rival Kenzie's. The two had become best friends and on Kenzie's 17th birthday he took her to meet his mother. Kyung-Hee had been planning on cutting all ties with the coven and moving back to Seoul but she couldn't do that, not a second time. So all she needed to do was to have a spark ignite so she could be rid of the 'witches' for good. Kenzie was the spark she desired and the three of them told mortals of the coven of witches. By the time Kenzie had left for her curfew, the coven was up in flames.
The friends had planned to meet at midnight in their usual spot in which they would leave for Seoul along with Kyung-Hee. But when Kenzie wasn't there, alarms started to ring inside of Sang-Hyuk's head and he ran to the coven through the hole he and Kenzie used often and searched for her in the chaos. He checked a few buildings before hearing her scream. Rushing to the building he saw Kenzie and attempted to save her by holding out his hand, urging her to take it so they could run away. As she reached out, a burning beam fell from the roof, causing the two to retract their arms quickly. Sang-Hyuk stared in horror as two of the elders took Kenzie. As he saw her disappear into the distance the building began to collapse around him, in which he screamed for help. An disguised demigoddess, who was nearby, heard the screams and was prepared to kill Sang-Hyuk before realising who he was. The woman saved Sang-Hyuk who took him to her home where she treated his burns. Unknown to him, his mother had left for Seoul without him, believing him and Kenzie to be dead.
The woman who had saved him was a daughter of Boreas herself and had received a dream from her father to take Sang-Hyuk to Camp where he would be safe. The woman, Henriette, decided to wait on it for Sang-Hyuk to heal completely. After a few months he was completely healed and was escorted to camp where he was claimed by Boreas.