MARK?

Since vampires in this world don't necessarily need blood to survive, the act takes on symbolic meaning: control can be either gained or lost through this action, the act of blood sucking.

Following the war between the humans and the vampires, the peace treaty stated to have banned vampires from drinking a human's blood unless the contact was voluntary. Apart from that, human blood was a luxury for the citizens of the Draconian empire. They could purchase bottles of human blood sold in the market, which was of course voluntarily sold blood. Humans with different blood types sold their own blood in the market as it was a two way beneficiary transaction. The humans got a good load of money for their sweet blood, while the vampires got the thing they desired.