Actually, Hao Ren already had a vague feeling that the vampire maiden possessed many secrets earlier on. This was not only his intuition at work, but there were many signs that were hard to ignore.
Frequent sleep and loss of memory, a completely different habit from that of a normal Blood Clan member, a series of abilities that only she herself could master, and her weird "body", which could divide itself into transcendent bats. All of this was enough to make Vivian a particularly special individual. What made it even more interesting was the sculpture they found in the ruins of Olympus, and the recent "evil spirit" incident. With so many incidents, who would not have suspected it?
However, Vivian had lived for over 10,000 years and she seemed completely fine.