Steamwalkers

"It was the night me and Jimmy Half-a-Hand was casin' the old silversmith's shop, up there on Brimming Way. We'd just decide to move in an' crack the side window, which was Jimmy's special, see. Then we hears this hissin' sound, like a boilin' pot or sumfin, an' then there's this uncanny red light shinin' in some mist or steam that weren't there before. The next thing I know, Jimmy's screamin' bloody murder, an' missin' the hand that was still there; it was floppin' around an' there's this ragged old skeleton, right? Only it's walking, an' sparks are flashin' up and down the bones, an' the eyes, there're like lookin' into the pit of the abyssal maw itself, I tells you. Now me, I was standin' back, so's maybe it didn't think I was involved. Or maybe it thought I'd spread the story. I don't rightly know. But it tore poor Jimmy apart with this wicked metal claws on the fingerbones, ain't never seen nothin' like it since. An' then, when Jimmy stops screamin', an' I'm still standin' frozen, I don't mind tellin' you mate, frozen with absolute panic, it just turns away an' walks off in this cloud of steam, leaves me alive and Jimmy a bunch of parts for the homunculi vats. That's when I swore off of ever thievin' again, mate. Turned me as straight as a ruler. I still wake up some nights in a sweat, dreamin' about that thing and Jimmy screamin'. Them steamwalkers is nasty business, and no one in his right mind would want to tangle with one."

-Jacob Snow-hair, regarding the Steamwalkers

Full Description

Steamwalkers, at first glance, appear to be little more than animate skeletons, shrouded in a cloak of steam and mist as they stride along, dull crimson light seeping from their eye sockets; indeed, this is the appearance they are designed to give, the better to terrorize those they are built to hunt.

A closer look reveals that the skeleton is articulated by fittings of brass and oiled leather, with thick bundles of copper wire running through the spine and along the limbs, feeding into small thaumatechnological devices that animate the entire construct; the wires, in turn, run both into the otherwise largely sealed skull cavity, and merge with the compact steam engine wedged into the torso amid the ribs, generating both the steam that shrouds the skeletal figure and the power that drives it. Small runes etched on the engine's boiler ensure that it draws every last calorie of power from the alchemically augmented coal that fuels it.

The crimson light comes from a component that is, perhaps, even more important than the machinery that drives the ungainly-seeming beast: a large crystal resides in the skull cavity, with a fine mesh of copper wires that wraps around it and connects it to the thaumatechnological systems. It houses the captive spirit of a condemned criminal, bound in death to serve the society it was deemed a traitor to in life. Trapped in a torpid, largely unaware state, the spirit's memories of life serve as an operating program for the construct, enabling it to move, and providing a certain level of awareness that lets it recognize when other, still-living mortals are engaged in criminal activity.

Lastly, often overlooked due to the bloodstains that make them blend into the often-dingy-looking skeleton, many steamwalkers have had their finger bones replaced with long, sharpened blades, making them vicious predators when they happen upon unlucky criminals. While not particularly cruel, as they lack the self-awareness to be capable of such a notion, the steamwalkers often fight in such a way that their victims bleed to death from dozens of small and horrifically painful lacerations long before the construct manages to strike a fatal blow.

Creation

"Prisoner #1705, known as Jameson Cooper, was sent to the Scholam Necrosis today to fulfill his sentence: death and recrafting as a steamwalker. His remains fetched six crowns three fangs, and his bones are expected to be walking in a week's time."

-Justicar Kurun, logbook entry

There are, to be sure, much more durable and powerful ways to build guardian automata than the methods used to create a steamwalker. Few, however, are as effective at terrorizing the criminal element of the city. Stories of the shambling, mildewed skeletons with frightfully swift reactions and razor-sharp talons quickly circulate in cities which employ these strange thaumatech constructs, and soon only the desperate, the determined, and the deranged dare to ply the criminal trades.

A steamwalker is crafted chiefly from a condemned criminal. Psycho-thaumaturges attend the condemned in a special execution chamber, recording the patterns of his mind into a specially grown and shaped piece of crystal at the moment of his death. The spirit still flies free into whatever afterlife exists for it, but the mind is preserved, frozen at the moment of flashback when every memory is relived at once, every skill's progression perfectly recalled. A successful capture leaves the crystal alight; most often the crystal matrix is designed specifically to shift the light to a hellish red to prey on the fears of the populace.

The criminal's body is then carefully divested of soft tissue, which is sent off to be sold to some bio-thaumaturge or fleshcrafter or homunculus farmer, while the skeleton is carefully treated with preservatives and the bones are all reinforced with iron and bound together with leather straps and brass rivets. A compact, powerful steam engine is secured in the skeleton's ribcage, a complex glyph etched on it to ensure function and efficiency; from this, a complex elyctrical system is run out through the spine and along the major bones, along with pistons to give the construct a full range of motion. The fingertips are filed down, and alchymically augmented mortar used to bond razor-sharp claws of sturdy iron to them. Finally, a complicated network of metal threads are woven through the skull, securing and interfacing with the frozen image of the condemned individual's mind. The top of the skull is replaced and mortared down, and all the skull's opening save the eye sockets are sealed up, letting the inferno light glow through.

It is this crystalline snapshot that allows the construct to walk in a bipedal fashion, and gives it the rude awareness that lets it identify those using the skill set it once had in life; in addition, the nature of the crystal is designed, during formation, to encode the laws of the city or nation into it, further letting it recognize that a crime is being committed.

From there, the construct becomes judge, jury, and executioner; anyone it catches in the act of committing a crime is, in most cases, summarily executed, the carcass left for the city residents to find. Some few are more finely tuned, acting to capture the criminals they find and drag them to the jails in an implacable grip of metal-reinforced bone for sentencing.

One unfortunate peculiarity of the crystalline 'brain' is that the constructs function most effectively in their old haunts from life, and inevitably wind up drifting there. To have steamwalkers present in one's neighborhood is a sign of criminal activity at some time in the past, and often those neighborhoods which have none, or at least very few, on their streets pride themselves, snobbishly, as upstanding citizens, looking down on anyone who lives in more infested locales as potential scum.

Additional Information
-Steamwalkers are not undead; they are constructs, built with bone to maximize the amount of terror they can generate when they appear.
-The steam engines wedged into the ribcage are compact and efficient, but most steamwalkers have routines coded into them to let them keep functioning by refueling the furnace with alchymically doped coal kept on their belt, as well as topping the boiler off with water from rain barrels and similar sources.
-Steamwalkers, despite having open eye sockets, do not see in the normal sense; they possess thaumaturgic senses that let them perceive the material world, psychosphere, and aetheric overlay in a sphere of awareness that extends out to roughly 150 feet. The sockets are open solely to enhance the terrorizing effects of the construct.
-They have no minds to speak of; the mental snapshot in the crystal is frozen in time, a still life of the now-dead mind that serves as a template for the construct's behavior and awareness. Their awareness is on the same level as a complex plant.
-In an emergency, the steamwalker can dramatically increase the amount of power it has available, at the cost of shortening operating time; in this mode of operation, visible arcs of lightning sizzling along the wiring wrapping the bones, and the construct moves with greatly increased speed and strength.
-As a last resort, the construct can overload the furnace, superheating the boiler within a minute; the resulting detonation is extremely deadly, as it sends searing-hot metallic shrapnel flying, often cutting down anyone trying to close in on the construct, and even those who try to flee before it explodes, as it can operate right up until the last second.

Plot Hooks
-A criminal who has been caught and condemned has information the PCs need; they must either rescue him from the prison before his execution, or find a way to extract the knowledge they seek from the crystal in the resulting steamwalker's skull. The construct, of course, will regard any attempts to retrieve the crystal as an assault, and react in self-defense.
-An undetected flaw in a crystal has resulted in a steamwalker behaving in a deranged way, misunderstanding normal behavior as criminal activity. Can the PCs track it down and deal with it before it becomes the deadliest serial killer the city has ever known?
-One of the psycho-thaumaturges has a long-harbored grudge against certain public figures; she introduces specific flaws into the crystal's growth, creating an assassin construct that will always see anything these figures do as criminal activity. Can the PCs track down and stop the construct before tragedy results? What if the figures are actually guilty of some horrific crime, and the PCs discover this just before finding the construct?

This sub was largely inspired by Ouroborus and his work on Locastus, specifically the Deaders. That, and the notion of a steam-shrouded skeleton lurching out of a bank of fog, with a mantle of steam, struck me as an interesting one. And what better way to catch thieves than to set a former one on them?