Where common archaeology can uncover the origins of technologies which were later built upon or superseded, its more esoteric counterparts sometimes reveal things beyond our current understanding.
The instantaneous transit of a person from one place to another - or the appearance of the same - is an aspiration demonstrated in countless speculative presentations of science and magic. While most will, understandably, assume that this ambition begins and ends in fiction, there exists at least one reliable and reproduceable method to produce such a result. There is a cost though; a price steep enough that even those versed in the theoretical details and with the resources to commit to the necessary preparation often baulk at the final step, unable or unwilling to put themselves through the attendant physical and psychological trauma of such a journey.
The technique is organic in nature (rather than mechanical) and requires the growth of a rather unique species of tree at the intended points of entry and egress. Now referred to as Zagreus Greys, what little is known about their origins - and whatever they might once have been called - suggests that they are some manner of supernatural cultivar; a hybrid synthesised from flora and fauna which were fused using some manner of protean sympathetic magic. Grotesque and unnatural, buried within the disguise of a coarse and brittle bark, is a mess of animal biology - a five-chambered organ spilling out, red and raw, from between wreathed coils of cellulose-stiffened arteries.
The central chamber, a crucible sealed with a knotted sphincter, is by far the largest. Acting as both stomach and womb, it is responsible for either destroying a person who has been placed within it (transmitting) or for reconstituting a person who has been broken down by another Zagreus Grey (receiving). The initial stage of ‘transmitting’ is the best-understood of any part of how this process unfolds; the dissolution of an organic substance into its chemical components is merely a matter of applying the correct mixture of enzymes and inorganic solvents. Everything beyond - especially details of how a person’s physical and psychological template are taken and transmitted - is a mixture of unproven theories, assumptions and best-guesses.
Once a person has been dissolved completely, the chamber constricts and contracts in an even, rhythmic peristalsis. The protoplasmic sludge is sluiced into and throughout the Zagreus Greys’ vascular system, mixing with an acrid sap that turns it into nutrients the tree can absorb. At the same time, another Zagreus Grey will be preparing itself to receive; rapidly growing a second lining - part amniotic sack and part placenta - within its central chamber. The smaller chambers express a mixture of proteins and amino acids into the sack and, less than ten minutes later, the transmitted person is ready to be reborn (having travelled faster than via even the most modern technologies).
Using Zagreus Greys for transportation makes formerly-philosophical questions about the nature of the self urgent and immediate. The physical form is reproduced with minor cosmetic variations, the mind apparently without even these irregularities, but nonetheless from matter distinctly not shared with the original. Even the terminology (transportation over teleportation) demonstrates an unease with the process; the sense that something intrinsic but ineffable is lost between the destruction of one body and the transmigration of the psyche into a new, nearly-identical physical form. Despite our most intrusive experiments and examinations, we are ultimately forced to take someone who has used a Zagreus Grey at their word when they assure us that they are still themselves.
This uncertainty - along with the rise of options that traded some speed for comfort and other conveniences - might have been among the reasons for the historical abandonment of using Zagreus Greys, though the physical pain was almost certainly a factor. To be transmitted feels like drowning and burning all at once; like dying, slowly. It is the acid scream of flesh catching fire and melting away as a wash of enzymes unravels proteins, turning one’s body into a choking soup. It abates only briefly, a moment of dull and senseless tranquillity before the agonies of coming back to full and complete consciousness in a body that is still being rebuilt.
What follows is the trauma of being born, but without the luxury of forgetting. The amniotic sack - slick with gore and covered in a mesh of temporary blood vessels - is expelled from the central chamber intact and, if the rebirth is not being midwifed, one must tear oneself free. Nails and teeth that have not set to their proper hardness trying to rip and bite a way out, beset by the panic of suffocation, it is an undeniably terrifying experience. In more-coordinated circumstances there are people standing by to offer assistance; a sharp blade to split the sack in a single, assured cut and some food to help settle the nausea of a stomach that has never been filled before.
Choosing a point at which to exit the network is relatively simple, though it is another aspect of the process that currently defies explanation: A traveller only has to concentrate upon the image or the idea of the intended arrival point. If someone enters the chamber without such specific intention, or without knowledge of what is happening to them, they will be received by whichever tree is closest to the location with which they have the strongest psychic resonance. This is often where they were raised, or some other site of particular emotional significance, with the belief being that the Zagreus Greys will default to proximal familiarity in the absence of more deliberate instructions.
Although there is still nowhere near enough information to infer any meaningful details about who created them, or the circumstances that necessitated such an invention, some evidence of their origins comes from the occasional discovery of ancient and untended specimens. Possibly wild (but generally assumed to represent points on a planned network that fell into disuse) these Zagreus Greys sometimes intercept and birth people in transit, though this appears inadvertent. When such specimens are found, they are usually relocated and transplanted - to take advantage of an already mature and viable tree - but are sometimes destroyed in order to prevent further such potentially-lethal accidents.
These incidents seem to be significantly more likely to occur when the shortest path between the point of entry into the network and the intend point of exit (as mapped over the surface of the Earth) is disrupted by the presence of another Zagreus Grey. Since their rediscovery, their use - undesirable even in the most dire and desperate of circumstances - has largely been in aid of attempts to understand how they function and solve the mystery of their creation. Though statistically safer than even flight - the safest of the purely technological ways to travel - in terms of deaths, using Zagreus Greys does offer one unique danger.
An interrupted transfer (if the transmitted body is removed once the process is underway, but whilst it is still alive) can result in a doubled consciousness, a mind split into two equal and identical parts that occupy the ruin of a body mid-dissolution and its unfinished replacement simultaneous. The shock and disorientation of the bilocation of sensory input, exacerbated and multiplied by the various agonies of inhabiting two failing bodies, leads to an inevitably painful death. These potential dangers - and the promised agonies of even perfect functional - have rendered Zagreus Greys the choice of last-resort as a means of travel, especially against the ongoing advances in both communications and transportation.