The Bone Concubine was quite flexible, while the Imperial Concubine was rather haughty.
After a series of fierce and rapid encounters, and upon hearing that both the Soul Concubine and Blood Concubine had agreed to follow him, these two no longer resisted and chose to accept as well.
In truth, though they were willing to die, it didn’t mean they wanted to.
Joining the demon veins was their original destiny.