The Eternal Night Clan, had stolen the power of eternity.
Similarly, as punishment, they were ostracised by the living creatures, forsaken by the gods.
Even though eternal, they would only live in darkness and solitude.
In order to thrive better in the old castle, the Eternal Night Clan began to require dependents and servants, giving their blood to those living creatures who craved eternal life.
Transforming them into the long-lived Blood Clan.
And the price of this extended life, is the dependence on blood, it can also be called bloodthirst.
The Blood Clan began to prey on humans, thus affixing them with the title of vampires.
And it is believed that, all members of the Blood Clan drink the blood of living creatures.
Of course, Fang Hao didn't understand these things, he couldn't distinguish which ones were vampires and which were not.
The media he had contact with, suggested that all vampires drink blood.