The Occido Lumen recount of the vanquish of the fallen angel Azrael not only explains the nature of the vampires but gives insight into the makeup of the world. In The Strain story-verse or cosmogony, the arbitrariness of cosmic constants and factors in nature are a result of the world being created, making it possible for creatures and other aspects of creation to be formed of worldly elements but bearing symbols and portents.
Signs and Omens
The Lumen reveals vampires as one particular creature whose nature is known to be marked with meaning or significance, reminiscing the curse placed upon humanity during its own Fall as ascribed by People of the Book. The vampires are averse to the earthly representations, namely silver, the sun and running water, that their progenitor Azrael was condemned to endure as punishment for his violations of nature:
- "Silver, the closest substance to the [angel] blood they drank, would forever have an ill effect on them. The sun, the closest thing to God’s face on earth, would always purge them and burn them away, and as in their very origin, they would remain trapped between moving bodies of water and could never cross them unassisted." - from The Night Eternal
Meaning or significance is indicated in other cosmic events in 'The Strain' story-verse where normal scientific phenomenon such as an eclipse or a comet could denote arcane knowledge that might be decoded through mantic arts (prophecy or divining knowledge of the unknown), considered sciences by scholars in antiquity. God is depicted more like sentient energy than entity, while the Ancients, more sentient substance (through their "white and worms") than creature, are suggestive of perversions of this elevated state of connectedness.
The Natural Order
While science is reluctant to recognize perversion or corruption of nature and the natural order (since everything would be natural), in 'The Strain' story-verse unnatural circumstances occur. The strongest evidence of prohibition against this corruption, apart from being voiced by characters, is the inability of the Ancients to possess the unborn through the flesh-burrowing worms, even though they may yet be infected and transformed through some viral agency. When the leader of the Sun Hunters declared Neeva's daughter corrupted in the Season 1 episode "For Services Rendered", he would necessarily be referring to her having the worms, unlike a free agent such as Quinlan, who was merely transformed but not possessed.
This insulating condition against otherworldly usurpation is derived from the concept of the "sanctity of life" found among traditions of the People of the Book and implies that the world, though created, operates under its own established rules that are not to be tampered with by creatures of the other realms of existence such as angels. The possession of victims' essence and will by the otherworldly Master proves a transgression of those state of affairs, particularly where free agents are concerned.
Such a separation of realms would allow worldly events to unfold their destinies according to their own laws or allowing interaction with the world solely in terms of those same governing laws. This worldly state of affairs might be compared with the concept of the "best of all possible worlds" formulated by philosophers like Aquinas and Leibnitz, facilitating or accommodating free will and naturalistic interactions.
The Physical Plane
To act in the world requires being part of the world, however angels had been in the world without being part of it, as stated in 'The Night Eternal':
- "These physical sensations were new to all three of the angels, but for Ozryel (Azrael) the sensations were overwhelming [....] Ozryel had come to earth many times. [...] But he had always traversed this plane in spirit form, his essence still connected to the Lord, never having been made flesh."
Physical characteristics of vampires emerge from the worldly trappings assumed by their progenitor, Azrael, who became incarnated (become flesh and "blood"), since angels in their true state are incorporeal intelligences: pure mind or spirit. The Ancients are infused with a sentience derived from their angelic origins although not angels themselves, but their incarnate source provides the material basis for them as virus, parasite and organism, emulating the workings of earthly creatures.
As a result, the functioning as a species governing those who are corrupted would still follow a biological logic despite being hijacked by the unholy will of the Ancients. Biologically, whatever viral-like mechanism exists, efficiently modifies bodily functions towards vampiric purposes, while the worms serve as delivery mechanism and biohazard extending the contagion of the species along with the corrupting presence of the Ancients themselves through possession of free agents.