Comment by Qiqi on Introvert

You remember seeing her wife heavily pregnant with his child but she died before giving birth. So actually Eirin is a Dragon and her powers are really powerful so her mother couldn't handle it and passed away before giving birth. So the actual twist was that it was Cha Misoo (The real Eirin in Korea) asked a dragon to save the baby by digging her mother's grave. So yes Eirin is his biological daughter who was given to a collateral family of Etham household. They thought she was their illegitimate child because the other dragon used their powers to alter their memory.