Why does the Master Vampire remain a vampire? I thought the curse had already passed on to Vlad. Shouldn't the Master Vampire be freed from the curse?
See my answer for this question. The short version is that the nobleman was cursed twofold - his transformation into a monster, but also his confinement to the cave. As he explained to Vlad, his confinement would endure until he could find a righteous man to take on his curse.
By willfully accepting the curse of the vampire, Vlad freed the nobleman from his confinement. The transformation, however, is permanent.
Someone posted a non-formatted transcript here, it seems the way the curse worked was that Vlad had three days to resist the temptation to drink blood, if he did he would return to normal after that time (the Master Vampire doesn't say what would happen to himself in this case, perhaps he would just remained trapped). But if Vlad gave into temptation, Vlad would become a vampire, and the Master Vampire says of himself that he would then be "liberated", and "I then darkness gave a worthy sacrifice. You will be his vessel, as I am." It's not clear from this line alone whether "liberated" means "freed from the cave" or if it means the Master Vampire would die (and whether the 'sacrifice' refers to Vlad or the Master Vampire), but the Master Vampire also goes on to say "And I'll be free to let everyone who betrayed me my revenge loose. And you will one day serve me, my pawn. In a game of deadly revenge." (At least I think those are all his lines, the dialogue isn't attributed in the transcript.) So that would seem to indicate that if Vlad drinks in those three days, the Master Vampire will be "free", and will then use Vlad as a pawn.
Here's the dialogue in question, I've added who I think is speaking each line although I'm not sure:
MASTER VAMPIRE: I was centuries caught at this place. I'm stuck in this cave, condemned by those who betray me. I've waited a long time for someone with your strength. With your gifts, your will. A man, worthy of the dark...and all his powers. If I am your salvation, you are mine. Drink, you'll feel my power. And the forces of 100 men. The velocity of a falling star. Predominant on the night...and all its creatures that see and hear through their senses. Even your wounds heal naturally.
VLAD: At what price?
MASTER VAMPIRE: Your thirst. Once you drink blood for human blood insatiable. But you can withstand three days...then you return to your mortal state. After encountering my strength. And maybe you than save your people.
VLAD: And if I drink blood?
MASTER VAMPIRE: The consequences will be worse. I will be liberated. I then darkness gave a worthy sacrifice. You will be his vessel, as I am. A scourge on this earth. Destined to destroy all ... And I'll be free to let everyone who betrayed me my revenge loose. And you will one day serve me, my pawn. In a game of deadly revenge.