The Great Vampire Conspiracy
Conspiracy theory
Kings and thanes of Freynia among the rich merchants and eccentric scholars have been put under scrutiny for decades. This is not unusual, as those with limelight are always under inspection, but there are few other places where such people are first accused of making a pact or being a vampire themselves.
Indeed, in Freynian soil, there are far more sightings of vampires than anywhere else in the known world, was it out of superstition or genuine larger vampire population. And while the nobility has repeatedly told that they would take care of the vampire blight, nothing seems to stop the nightly terrors caused by these bloodsuckers.
Are these great beasts truly out of the reach of the most powerful, or is there something far more sinister going on?
Summary
Believe among commoners is, that to keep their power some of the nobility have done deals with demons or devils to keep their relevance, and the vampires are the manifestation of these contracts. Other popular suggestion is that vampires are used as crowd control, keeping their subjects inline and fearful.
Historical Basis
Despite the popularity of the theory, there is very little evidence that would support thought not enough counter-evidence to completely dismiss it either. While the prominence of vampires might be due to other factors, it is very possible that vampire lords have allies among the populace to keep them hidden and secured. This could well include people in power.
Variations & Mutation
Some people have noted how similar certain family members of highborn family look and speculate that the families might actually be formed by vampires who take turns on which of them is the visible face of the family in any given time, to keep suspicion at bay.
In Literature
Vampire menace has made into popular subject of literature, with poems that told kids to stay safe at night to thrillers and encyclopedias about the subject matter. There is also a sizable proportion of romantic novels that use vampires as a villain or toxic lover, to make the true hero of the story seem far more desirable. This considered as a cheap trick by literary critics but is relatively popular among readers.
This is a really believable conspiracy theory. I particularly like the detail that they think the nobles swap out the head of the family every so often to avoid suspicion.