A nameless serf offends the wrong noble and is dragged to the altar as a sacrifice for the vampire progenitor. Instead of dying, he strikes a bargain and walks away carrying a piece of the progenitor's own blood power.
He uses it first on the wolves tearing through his village, then on the famine the nobles let spread because starving people are easier to tax. The locals start calling him a hero. That draws the attention of the same nobility who tried to kill him, and of a queen cornered by their conspiracy, and he has to decide how much of the progenitor's power he can carry before it starts carrying him.
