The Burning of Ald Sotha
Sotha Sil was born into one of the minor Chimer houses of the Morrowind frontier in the early centuries after Veloth's pilgrimage. The house is remembered chiefly for the settlement that bore its name, Ald Sotha, a town that no source describes as politically important and that the world would have forgotten entirely if not for what happened to it.
What happened to it was Mehrunes Dagon. The Prince came to Ald Sotha on a rainy morning, without warning and without mortal summoner, and he and his host destroyed the town in a single attack. The Chimer had taken themselves out of Azura's protection at the founding of the Triumvirate, and the First Tribunal had no obligation to defend a people that had repudiated it. There was no political calculation behind the attack and no theology behind it either. The town was destroyed because the Prince of Destruction could destroy it.
The houses were already burning when their inhabitants woke. No member of House Sotha lived through the morning, save one. The survivor was the boy himself he was pulled from the wreckage by a young mercenary of obscure birth named Vivec, who had been near Ald Sotha by chance or by the kind of chance that follows Vivec everywhere. The two would not be separated again for the rest of the Daedric Era.
The first sermon of The Thirty-Six Lessons of Vivec contradicts this claim, placing Sotha Sil as older than Vivec. According to the texts, the Demiprince Fa-Nuit-Hen appearing to a Velothi tribeswoman, the wife of a Chimer netchiman, who had been impregnated with an egg by the dreugh before being brought to Azura's Coast by Sotha Sil. The egg contained the unborn Vivec, and seven Daedra known as the Barons-Who-Move-Like-This appeared before the woman to teach the egg new swordsmanship motions. When Fa-Nuit-Hen appeared, he told the netchiman's wife to seek the Hortator in the land of the Ascadian Isles before combining with the Barons to form a terrible pillar of fighting styles and teaching Vivec. Fa-Nuit-Hen himself verifies the sermon's claims to a degree, stating that he did in fact meet Vivec in his youth, and made an impression on him.
The Engineer
What Sotha Sil became, in the years after the burning, was an engineer. The sources agree that the boy who walked away from Ald Sotha was already given to mathematics and to the patient counting of small things, and the discipline of an engineer was the natural shape for such a temperament to take.
His early work was practical. He made tools, and improvements to tools, and the kind of small mechanisms that made the daily labour of a Chimer settlement less brutal than it had been the year before. He was sought out by smiths and by farmers before he was sought out by lords. The reputation he built in those years was the reputation of a useful young man, and it is on that reputation, and not on any claim of greatness, that the rest of his life was raised.
The greatness came with what he found beneath the ground. The Dwemer had by this point withdrawn from the surface for many ages, but their old workings were not all hidden, and a determined Chimer with a head for mechanism could learn a great deal by walking into one and looking carefully at what was there. Sotha Sil walked into many. He took apart the simpler animunculi he found, and he reassembled them, and he built lesser versions of his own. The soul-craft that the Dwemer had received from Azura through the First Tribunal was not yet known to the Chimer in any systematic way, and Sotha Sil's earliest constructs were powered by cruder means. Even so, he made them move, and stand, and obey, and a Chimer noble who had not previously taken an interest in the boy from the burned town began to take one now.
It was through these constructs, and the philosophy of order they implied, that Sotha Sil first conceived the project that would consume the rest of his existence: a city of pure mechanism, ordered to a single will, free of the imperfections that the Aedra had built into the living world. He did not have the means to build it yet. He had the idea, and he wrote it down, and he kept the writing.
The Tactician
The Chimer of this period were not a peaceful people, and a young engineer of growing reputation was inevitably called to apply his mind to the problems of war as well as of craft. Sotha Sil proved as gifted a tactician as he had been a mechanist. The same mind that took a centurion apart and rebuilt it could take a battlefield apart and arrange it to a desired end, and the Chimer war-chiefs of the early Daedric Era began to consult him in the period before any campaign of consequence.
Two of his students from these years would matter more than the rest. The first was Nerevar, already a war-chief in his own right and married to the healer Almalexia, who came to Sotha Sil for the refinement of a tactical instinct he already possessed. The second was Vivec, who had grown from the mercenary who pulled Sotha Sil from Ald Sotha into one of the most effective field commanders of his generation, and who came to Sotha Sil to learn the discipline that would let him keep what his instinct had won. Sotha Sil taught them both. By the close of the period, the three were close enough that Vivec could approach the older mer with a proposal that no other student would have been permitted to make.
The Heart
The proposal was apotheosis. Vivec had reasoned, by some path the sources do not preserve, that the Heart of Lorkhan at the foot of the Red Tower could be drawn from, and that a sufficiently disciplined party could draw enough from it to put themselves beyond the reach of the Princes for good. To Sotha Sil the argument carried weight that it would not have carried for a different mer. He had measured Princely intervention in mortal affairs against his own family's tombs, and he had concluded long before Vivec asked him that the Princes were a problem to which only a permanent answer could be addressed.
He agreed. Almalexia agreed with him. The three went to the Red Tower together and came down from it as gods, and what followed at Coldharbour and after is the subject of the entry on the Triumvirate.
What is worth noting here, and what the entry on the Triumvirate cannot dwell on, is that the apotheosis did not change the project Sotha Sil had been carrying since his youth. It gave him the means to build it. The clockwork city he had imagined as a young engineer in a Chimer workshop was now, for the first time, within the reach of a hand that could reshape matter at its will. He set to work on it almost at once, and he has been at work on it ever since.
The Clockwork City
The project Sotha Sil had carried since his youth came at last into the world after the apotheosis. He called it simply his City, though every other mer who has ever spoken of it has called it the Clockwork City, and the second name has stuck.
It is not a city in any sense a Chimer would have recognised. It is a metaphysical realm, contained physically in a brass globe no larger than a netch, hidden in the deep places beneath Mournhold. A visitor must be magically reduced before they can enter the globe at all. Within it the realm is expansive: it has a sky of its own making, the Celestiodrome, a horizon, weather, days and nights, all of them ordered to Sotha Sil's design and answerable to his will alone. It is said that even the taste of food within the City is a thing he decides, and that a guest whose palate disagrees with his arrangements has no recourse, for the laws of the place are not the laws of Nirn but the laws he wrote in their stead.
The purpose of the City is debated even by those who live in it. Sotha Sil himself has never written a clear statement of intent that the chronicler has been able to consult, and the Clockwork Apostles, his followers within the realm, have produced over the centuries a body of doctrine that is more sermon than explanation. The shortest honest summary the chronicler can offer is this: Sotha Sil regards the world the Aedra made as a flawed work, riddled with imperfections that the trick of Lorkhan and the diminishment of the architects baked into it from the beginning. The City is his attempt to make a better one. It is meant to be a Nirn rebuilt from first principles, ordered by mechanism rather than by Earthbone, free of the Princes' meddling and free of the Aedra's compromises both.
What powers the City is, in its own way, the most ambitious working in the realm. Sotha Sil did not draw on the actual Heart of Lorkhan for it, since the apotheosis had taught him better than most what tampering with that artifact costs. Instead he set himself the task of building one. The result, called the Mechanical Heart, is a constructed organ of brass and bound essence that imitates, at a much reduced scale, the principles by which the original Heart sustains the divinity of Mundus. It is not a true equal to the Heart of Lorkhan and it cannot become one. What it can do, and what Sotha Sil judged sufficient for his purposes, is provide a stable wellspring of power adequate to keep an entire pocket realm in continuous operation, and to keep Sotha Sil's own divinity replenished within that realm without recourse to the original Heart at all.
The population of the City is in three parts.
The Clockwork Apostles are the closest thing the realm has to citizens in the ordinary sense. They are dunmer, and the rare man or beastfolk, admitted by Sotha Sil for some demonstrated mastery of magic, mechanism, or another discipline he has judged useful. An Apostle who has earned the standing replaces their original limbs, in stages, with clockwork prosthetics of Sotha Sil's design, until what remains of the original body is a smaller and smaller portion of the whole. The doctrine they have built around their own modification holds that the synthesis of flesh and engineering is the first step toward the perfected being the City was made to produce.
The Factotums are mechanical servants of brass and bound soul, and they perform every labour the City requires. Some repair the works and the buildings. Some farm the strange grain that grows in the inner halls. Some cook, some clean, some guard the deeper chambers, and some are entrusted with tasks the Apostles themselves are not trusted to perform. They share a common voice and a common appearance, and their intelligence is structured around the function each was made to serve. To attempt to deviate from that function is, for a Factotum, not a sin but an unintelligible request, and the Apostles have been instructed in no uncertain terms that to tinker with a Factotum without Sotha Sil's permission is the gravest offence the City punishes.
The Fabricants are the third population, and the strangest. They are biomechanical creatures, neither beasts nor machines but a fusion of the two, grown rather than built. Some serve as labour beyond what the Factotums can accomplish; others roam the Radius, the wilder regions of the realm beyond the Apostles' settlements, where Sotha Sil permits an ecology of his own making to develop without close oversight. A traveller who passes through the Radius without an Apostle's escort is unlikely to return.
The Apostles' settlements within the realm are anchored on the Brass Fortress, the great population centre where the daily life of the City is conducted, and at the heart of the Fortress stands the Clockwork Basilica, the central spire from which Sotha Sil himself oversees the working of the place. Deeper still, beneath the Basilica, lies the Cogitum Centralis and the Throne Aligned: the chamber and the seat from which Sotha Sil reaches into every gear of his realm at once. The Mechanical Heart is housed there, in conditions the Apostles describe with great reverence and very little useful detail.