Vampires in Elstren are a consequence of an ancient curse. Apparently thought to have originated in southern Woodveil over two thousand years ago, stone tablets discuss a family cocoa farm found to be inhabited by strange, husk-like humans who feared the lamp-lights of the investigators. A neighboring farm was found to be laid to waste as well. There were records of that very farm through tithes just from months before, but the farmland appeared to be completely salted and the buildings were weighed by what should have been decades of age and overgrowth, and no one involved in the farm's operation was ever found again.

Strigoism is a transmissible, magical plague that afflicts only humans and wildkin. Strigoi form nests in dark, damp places, usually sewers or wells, from which they can stage regular feedings. A Strigoi which is not actively hunting or feeding rests completely motionless and silent, piled on the other Strigoi as a heaving mass. They appear as emaciated people, sapped of all vitality and humanity, with pallorous, dead skin, sunken eyes, and usually hairless bodies.

Strigoi break off of this mass to feed, where they will emerge at night and use the powers of stealth conferred to them by their status in order to hunt and feed from prey. Ideally, they drink non-lethally from a sleeping human victim who does not notice their presence. However, Strigoi have filthy, disease-ridden mouths, and their bite wounds tend to become severely, sometimes fatally, infected. Strigoi tend to hunt alone, but may hunt in packs if they are desperate.

Once they have fed, they return swiftly to their nest and resume being completely idle, unless something disturbs their nest. If their nest is disturbed, their mass breaks apart as the strigoi all descend upon the intruder, gnashing and tearing until the intruder is motionless and then quickly returning to their nest formation.

Strigoism is spread only deliberately. Strigoi will add numbers to their nest until the nest is at a capacity which the Strigoi believes sustainable, at which point they will only infect another person if a Strigoi dies or they reassess their sustainability. If the situation changes and feeding becomes more difficult, the youngest, weakest Strigoi are torn apart and killed by the rest of the mass to maintain the balance. They may choose to infect any human or Wildkin with a bite. When a nest is full, occasionally a Strigoi may break away from the nest to go start a new one elsewhere.

The exact magical source of this curse has never been ascertained for sure, as it comes from a kind of magic which is not presently known to academics. When a person is bitten by a Strigoi that intends to infect them, it exposes them to an unclear magical effect that causes their soul to blink out of existence, something which is otherwise almost never possible. Driven to maintain the 'momentum' that allows their body to continue existing, the new Strigoi form a psychic link with the others and will begin feeding in order to retain what little vitality they have left.

Strigoi can move at burst speeds of up to 250 miles an hour, meld with shadows such that it's extremely hard to notice them, regenerate from virtually any damage, and appear to slip out of human awareness constantly. It is hard to organize against Strigoi because even officials will easily forget they exist, and Strigoi escape notice when moving through shadows as humans struggle to perceive them without intent.

This is a consequence of their status as the most extreme form of Lacuna. Lacunae are objects or people on Elstren that are 'not intended by the universal blueprint' and which suffer varying degrees of rejection by the Architect. The most simple Lacunae are beings that burn in sunlight, but otherwise may live normally. Strigoi, and Vampires by extension, however, are so thoroughly antipathic to the universe that the universe itself actively attempts to write them out of existence.

Literature and knowledge of the Strigoi falls easily from history. Most people cannot describe or render the Strigoi because they remember them only as vicious shadows, and are horrified anew each time they witness them. People easily forget them entirely, and may struggle to notice them.

However, Strigoi burn extremely violently in sunlight, described as 'exploding pillars of scorching white light' when caught in sunlight. Even a second spent in direct sunlight will cause a Strigoi to practically explode. Strigoi are also highly weak to fire, only being able to very slowly regenerate from burns; fire is generally the only way to kill Strigoi.

Some people are capable of resisting this curse. These are either magical individuals who have wards that deflect some or all of the magic used to infect them, or people whose souls are so strong that, however weakened, they survive the effect and the Strigoi that bit them dies. However, if the curse is not resisted completely, the result is a Vampire.

Vampires are people who ostensibly lack souls, but unlike Strigoi, there is something left of them. Vampires appear to maintain a connection to the magic that was used to destroy their soul, and retain their humanity while gaining a variety of powers, but are still considered Lacunae and subject to some of those effects. This connection, an extremely bright point of light right where their heart is, is only visible on the Arcane Channels and tends to blind those who glimpse it.

Because of the narrow band of power required to deflect some but not all of the curse, Vampires are extremely rare on Elstren. Statistically, there are almost never more than ten at any given time.

Vampires have similarly superhuman speed to the Strigoi, can 'shadowstep' by which they disapper and reappear in another shaded location within sight, can meld with shadow in order to become practically undetectable, and in general are very hard to spot. They easily slip a mind that isn't trying to commit them to memory or perceive them, and so their most potent tool is stealth.

They regenerate similarly to Strigoi, and retain the same weaknesses to fire and additional weaknesses, particularly to stakes made from White Ash wood. Vampires cannot sleep, and do not need to but may eat or drink. They feed on human blood and vital energy, and gain more power depending on the power of the person they feed on. Unlike Strigoi, Vampires are very capable of surreptitiously feeding with their incredible stealth capabilities, painless and non-lethal bite, and hopefully good dental hygiene that prevents severe infection.

Vampires are a lesser degree of Lacuna than the Strigoi, indicating that it's the complete lack of a soul that makes the Strigoi so violently rejected by the universe. However, Vampires still suffer many of the effects; though people will usually remember them, their names and features may be easily forgotten, and over time writings about them and deeds by them may slip from history. Eventually, decades after they are gone, few people will remember a Vampire at all. The most clear example of this is that it's impossible to paint a Vampire's portrait correctly; their features will slip the grasp of the artist, even if the Vampire models for them, and it will always come out wrong.

Vampires will fatally burn in sunlight after about thirty seconds of protracted exposure, and even a few seconds leave lasting burns that will take weeks to regenerate from.

Though dangerous by themselves, a Vampire which has fed recently on a very powerful target can become catastrophically powerful. Vampires, though technically immortal, have an exponentially increasing demand for vitality. For centuries they may get by with feeding on humans, but their needs become harder to sate. Approaching a thousand years, a Vampire begins to lose themselves, unable to feel any satisfaction unless they completely eviscerate a powerful human and consume all of their organs.

In time, only Divine blood could sate their hunger, and unable to sustain themselves, they simply die. As Vampires get hungrier, they become more husk-like; when they're full, their blood runs almost as it did when they were alive, but when they're starving, it's little more than pallid ash. A Vampire that starves to death ends up looking quite like a Strigoi.

Strigoi, notably, are neutral to Vampires and will regard them with staring and little more. This is in contrast to Strigoi from other nests, with whom they will violently fight and attempt to kill. Vampires may even command Strigoi, but they frequently prove unruly and difficult to manage. Vampires are capable of siring another Vampire, but only once, at which point they become unable to infect others whatsoever.