Long before the Veil was created by the Elves and the Lurikeens, the forces of Nature and of Magic were as one, existing in harmony throughout all of Hibernia. Several locations in the emerald isle were crisscrossed with ley lines forming Nodes of extreme power and tranquility, most of which could be found in locations of extreme natural and ethereal beauty. The fey and mortals alike of Hibernia were drawn to these locations as the Nodes provided mystical insight and peace of mind to those who knew how to open themselves to them. The inherently magical creatures of the realm could nourish themselves on the arcane sustenance that was always plentiful within these nexuses of ley lines.
Due to the miraculous properties of these Nodes, many made shrines and temples to the Celtic gods of old, as the denizens of Hibernia felt that their connection to their gods and goddesses were stronger while in the presence of the ley lines. Likewise the inherent magic within the Fey were augmented greatly while in close proximity to these fonts of enchantment. Serene nestled groves dedicated to pantheons of Nature gods and mysterious towers built to study and harness the power of the Ether were tended by creatures of Nature and Magic alike, such as the Celts, Firbolgs, Elves and Lurikeens. Sadly, though the forces of Nature and Magic existed in peace, the children of such powers did not.
Despite the ongoing struggle between the races of Hibernia, a great monument was created by the Elves. This monument was a castle called Marrach Briollag and was lovingly built by the combined magics and abilities of several Elven Houses and allied Lurikeens upon an exceptionally potent Node.
Two elves in particular lead the effort in creating Marrach Briollag. Lord Nemanach and Lady Moriath of House Seun both were exceptionally talented workers of magic as were many in their House and they were instrumental in erecting the enchanted castle. For a short time after Marrach Briollag was completed, Nemanach, Moriath and the majority of House Seun dwelt in peace with the other noble Houses and allies who would visit or take up residence in the castle.
Before long however, other forces became interested in claiming Marrach Briollag, not only for its beauty, but for its location upon the powerful Node. Both the Unseelie and Seelie Court made political maneuverings towards House Seun, trying to win the House that they saw as having the most influential hold over the castle to their allegiance. Nemanach and Moriath had no desire to pledge fealty to either the Court of Summer Light or the Winter Court of the Dark, wishing instead to keep both at a distance, remaining neutral and keeping Marrach Briollag safe and unspoiled.
Whereas agents of the Seelie Court respected such decisions overall, the diplomats of the Unseelie were not quite so understanding. The Unseelie knew, through spies and informants, that House Seun had begun to take on a caretaker role for not only the treasured castle, but also for the people that had aided them in constructing it and who still lived within. The more both Courts had expressed interest and began applying pressure for a decision, the more Nemanach and Moriath grew paranoid concerning the intentions of their kin and what fate would befall their new extended family.
A ruthless Unseelie noble, Lord Ferghal of House O'Ciardha, used such information to devise a wicked plan and planted seeds of suspicion and distrust within House Seun that only stoked the flames of their paranoia to a new height. The false conspiracies and complex webs of deceit that Ferghal and his lackeys spun in Marrach Briollag did not involve House Seun however; instead the carefully implemented treachery insinuated that the members of other Elven Houses, that shared the halls with Nemanach and Moriath, were plotting to overthrow their Elven caretakers and claim the castle for themselves. The subterfuge did not stop there however, as Ferghal worked his lies upon said Houses as well. The Elves that they targeted did not possess the fortitude to withstand the subtle, corrupting magics of the Unseelie that were only enhanced in the presence of the Node. The insidious cantrips in conjunction with the venomous lies claiming that House Seun saw the other Houses as inferior and nothing better than servants was very effective in enflaming the proud people into an indignant rage.
In a very short time the labors of Ferghal came to fruition, and open hostilities began within the hallowed walls of Marrach Briollag. House Seun, with their control over the magics of Marrach Briollag and conveniently sudden aid of the Unseelie, overpowered the other Elves and Lurikeens, exiling them from Marrach Briollag forever.
After the conflict in Marrach Briollag was over, Nemanach and Moriath withdrew almost completely from contact with the other Houses and Courts of the Fey. Much to Ferghal's chagrin his plan only half worked. Where he had hoped that Nemanach would trust the Unseelie more after their aid in overthrowing the 'rogue' Houses and join them, the whole ordeal only threw the Lord and Lady into a descending spiral of sorrow, distrust and pain.
For some time Marrach Briollag was shrouded in an obscuring mist, fueled by the magic of House Seun and the Node, keeping others from finding it, up until the time when a great council held by the Elven race drew even Nemanach and his people out of hiding. It was there that the Elves came to the conclusion to create the Veil to attempt a more peaceful separation between themselves and the mortals of Hibernia. Nemanach and many others agreed to this although several wished to bring favored structures and places through the Veil into the Otherworld.
With the assistance of the few remaining allied Elven Houses from the other side of the Veil, the inhabitants of Marrach Briollag used powerful spells to begin the process of pulling the castle into the Otherworld only to find that halfway through the Veil Marrach Briollag was caught between the intense holds of the realms of Nature and Magic. With communication lost from both sides of the Veil, Nemanach and Moriath were trapped inside their beloved castle and were eventually forgotten by their own kin.
Horrified at their predicament, the already deeply suspicious Elves of House Seun blamed their fellow Elves for sabotaging and purposefully jailing them in revenge for their refusal to partake in the politics of the Courts and reluctance to open Marrach Briollag to outsiders.
As time moved on, the forgotten and imprisoned Elves became increasingly bitter and full of spite. The intensely magical nature of the Veil, being highly mutable and receptive to the emotion and thoughts of those who transverse it, took on a much darker appearance which in turn affected the castle itself. Marrach Briollag turned into a mockery of what it used to be, a twisted image of the beautiful, enchanting castle that it once was in Hibernia. Likewise the more hate and suspicion that welled up within the Elves, the more the Veil fed upon it and fueled that darkness into the Elves themselves. Over time their image changed to match that of Marrach Briollag and the darkness within their own hearts and souls.
Nemanach, in a rage at the situation he and his people were confined in, forever damned the name of his entire House and took on a new name that he felt was more fitting for his forsaken kin. House Seun was bade no more and House S'gath was created at his command as the dark elves took strength in all that was left to them, they embraced their new nature and began to revel in it. To further mock their despised and ironic existence of being trapped in the very place they had hid themselves in for so many years, Nemanach and Moriath declared themselves King and Queen over Marrach Briollag and claimed sovereign over their little domain in the vast Veil.
For centuries the now xenophobic dark elves have dwelled within their prison inside the Veil, mastering the mutable properties of the Veil which allows them to project their inner demons through illusory means upon their enemies. They have channeled the magic of the Veil to provide sustenance to Marrach Briollag, which acts like a cancerous tumor that slowly spreads its corrupting tendrils into the Veil surrounding it. The castle itself is alive with a malignant sentience and acts through its stone gargoyles, protecting its caretakers from all who would trespass into their domain.
Unfortunately for the people of Hibernia who now have a path opened within the Veil thanks to the Shar, Marrach Briollag has been discovered again, although those who may remember it will find its inhabitants are drastically changed and even less receptive than they once were.
What House S'gath and its dark elves plan to do with this new access to both the Otherworld and Hibernia, no one can say. What is known is that agents from the Seelie and Unseelie Courts have been dispatched into the Veil to verify the intent of their lost kin, and to see if anything can be salvaged from past mistakes.