A big part of the history of the Karnsteins relies upon understanding who nurtured this family, and why. It all goes back to the most ancient history of the undead, probably as far back as Atlantis. According to various accounts (including Marvel Comics), at this time several sorcerors created the vampire race while attempting to fashion a new kind of weapon against their enemies. Their plan went horribly wrong. Vampires proved far too difficult to control.
In time, the oceans drank Atlantis, but some of the undead survived. These few may as well be called Antediluvians, for they pre-date the Flood which ended that continent's history and civilization. Among these were Varnae, Rasolom, Qu'ra, and the entity that in time came to be known (by some) as the Patriarch (according to legend, a much earlier female entity, usually called Lilith was also a primal vampire, perhaps THE primal vampire--it isn't clear, although the name "Lilith" came to be used much as European monarchs like calling themselves Caesar--Czar, Kaiser, etc.).
He had many names. Which even vaguely resembles his original no one probably knows. Even he may have forgotten it. But certain patterns allow us to trace a little bit of his story as he wandered across the pages of history, dripping blood as he went.
- We know he was male.
- We know him as an ancient vampire (he even claimed to have brought about the fall of the Roman Empire).
- We know his thirst could rise to extreme levels, wiping out towns and laying waste to regions.
- We know him deeply interested in the breeding of humans, not least because he evidently had trouble turning others into vampires. Hence his ages-long efforts to foster those families (such as the Karnsteins) who could in turn become his progeny and minions.
- We know also he seemed actively Satanic or Demonic. Not merely evil in terms of selfishness and ruthless disregard of others. Worse even that cruelty. He seems something of a philosopher, an active worshiper of darkness and/or chaos.
- We also know that, unlike some (Dracula for instance) he seems content to remain totally behind the scenes, demanding abject obedience in those around him, but otherwise preferring the wielding of power over anyone's knowledge of it. This reflects in his attitude towards his (many) names.
Keep in mind there's no reason to believe the Karnsteins his only breeding experiment. Quite the opposite! Evidence strongly suggests he was behind the infamous Mitterhaus family (although they may well have interbred with the Karnsteins--so many records were lost). More, central Europe in the Renaissance and early Enlightenment fairly seethed with terrible stories of decadence, blood-lust and supernatural horror. Evidence of the Patriarch's undead hand?
At any rate, by 1863 a secret castle stronghold existed for the Patriarch (now using that name/title) and a court of followers, few of whom ever set eyes upon him. What we know of this location and events there come from notes by a young vampire named Mihel Beheim, who revealed that the vampires there reveled in the fostering of certain tasteful bouquets of bloodline, among humans/peasants servicing the castle. In that year a shocking crime took place among the assembled undead (some of whom almost certainly were Karnsteins).
By 1876, the Patriarch had decided to move to America. Perhaps the number of undead in Europe made his thirst more difficult to safely manage. Or it could be this formed part of a plan to expand his supernatural power. The town of Hangman's Corners, Texas, was his target. With him came an array of demonic minions as well as an occult ring somehow connected to the Old Ones (possibly Hastur). But in the face of unexpectedly powerful magical opposition, the Patriarch (referred to by others as simply The Stranger) fled.
This was hardly his only or even first foray into the New World. A Vermont town called Jerusalem's Lot, inhabited by an offshoot of the Shakers, vanished without a trace in the 1820s--victims to a wave of unquenchable thirst by this ancient evil. In 1850 a descendant of a leader of that group uncovered evidence of vampirism and demon worship (very much resembling that of the Old Ones) among his ancestors in the nearby town of Preacher's Corners. Rather than further what he calls a "polluted bloodline" he commited suicide, but an illegitimate son moved to the town to seek to redeem the family name--Boone.
The Nazi regime which Kagan (among others) helped establish furthered his long term goals admirably. Worship of death and chaos was the least of it. The SS breeding programs might well have given rise to vast numbers of potential recruits. Yet his efforts also brought forth their own failure. Hitler's Third Reich attracted the negative attentions of many groups and whole nations (including, interestingly, Dracula Prime himself). Meanwhile, Kagan's attempt to create an army of dhampirs from his loins spawned an implacable enemy--his daughter Bloodrayne. An ally of hers detonated a powerful bomb in the same room as Kagan--not killing him but wounding him severely. While his powers slowly healed him, World War Two was fought and (from his perspective) lost.
More speculative is the Patriarch's role in creation of the Corvini line of vampires, most probably by blending his own vampiric line with that of the alien Wamphyri.
The Masque of the Red Death by Edgar Allan Poe
The Vampire Virgins (unproduced sequel motion picture to Twins of Evil)
Vampire Circus (motion picture)
Metzengerstein by Edgar Allan Poe
The Golden by Lucius Shepherd
Tex Arcana (graphic novel)
The Garbage Truck by Stephen King
Jerusalem's Lot by Stephen King
Bloodrayne (video game)
Salem's Lot by Stephen King
Underworld motion pictures
Necroscope novels by Brian Lumley
AddendumI was one of the judges in the third Vampire Film Festival, and one of the films submitted for such was a short in which Rayne met Captain America. This is my (somewhat tenuous) basis for including Rayne and Kagan in the WNU.