Seokjin and you once was an angels. You and him was a partner that always come together and doing 'heaven mission' together. He's an angel of death while you're an angel of life. Even opposite, you both working together.

Until one day, some angels being 'envy' and blame some accident to Seokjin. Making him stop being archangel and now being a fallen angel while you're still an angel.

Now, you're in the earth to give birth (live) to humans. And then you saw him, Seokjin.