It was a thing made of shadows, but you wouldn't know just by looking at it. Its appearance was in the eye of the beholder, though if you looked at it full-on and for perhaps a little too long, you would notice something wasn't quite right -- you just wouldn't know that it was because your brain was creating its appearance more or less before your very eyes.
How it looked to the beings around it never really mattered since the shadows only knew one thing: how to do its job. Things needed doing, so it did them. Plain and simple, easy as that. This particular job pulled it toward a particularly seedy bar, but the shadows didn't notice that sort of thing. It could walk alone through every "bad section of town" without so much as a flinch, armed with only the knowledge that it could not and would not be harmed, so nothing really mattered -- save, that is, for being in specific places at specific times and handling business as directed.
Had someone ever explained to the shadows what a machine was at a very core level, it would have nodded and understood. Its sole purpose was to do as it was told in the most simple and direct way possible. Were it capable of enjoying its work, it would have, though it probably wouldn't know why.
The bar was crowded and loud, and had the shadows been paying attention, it would've noticed the place was full of locals, some talking, some dancing, and almost all of them drowning something in alcohol, be it sorrows or perhaps their standards. Its mark was in the far corner, a scrawny young thing chatting with a significantly older gentleman who kept plying him with drinks. The shadows paid attention for a moment, a brief flicker of doubt crossing its mind.
The young man? it wondered, while everything around it throbbed a silent yes. Honing in on him again, the shadows saw his being as a flimsy wrap-job around copious amounts of flailing darkness. If the shadows smiled, it would've managed a smirk. But the truth was, it didn't exactly have a mouth, therefore never actually having a reason to learn how to smile, which was almost a shame. If it ate, this would end with the perfect meal -- but it didn't eat, and would therefore miss out on the likeness completely.
It crossed the room without much notice, until it stood beside the mess of a young man who had recently drained his drink. His old-man companion found himself heading to the bar to refill his drink for some unknown reason, leaving the scrawny boy alone with it. The shadows knew he was talking, most likely having a conversation with it that it was not actually participating in, but this was how it worked. Within minutes, it was drawing the young man outside and down the nearest alley by some pretense that only the young man himself would know.
There was no one near, this much it knew. It didn't care, but a lack of witnesses was far simpler and much more productive and safe. (Why clean up the universe if it would cause more messes in the process?) The boy stood in the alleyway, only half-gazing at the shadows, just inebriated enough to know something was wrong. He kept fumbling with his clothes, starting to unbutton his sweater and then stopping, beginning to take down the zipper of his pants and then pulling the tag up again. It would've been amused, were that even a possibility. But now, it was on.
The shadows leaned toward the young man and knew his darkness was being jostled under the boy's thin casing. He probably believed this person had just pushed a few fingers against his chest, which wasn't exactly the case.
The scrawny man shuddered for a moment, his eyes now wet and wide. "I've done bad things," he squeaked, his voice suddenly shaky. "Please..."
Consent was neither given nor taken away by the time the shadows were upon him. Had someone been watching, the boy would've appeared consumed, almost blinked out of existance. But in reality, he was more or less being ripped open and emptied into the void that made up the shadows, not unlike a crab pulling a coconut apart to get at the fleshy bits inside.
In the end, his darkness was destroyed, as was the thin veneer keeping his chaotic inner self intact for small amounts of time. His memory would remain for a while, but like all memories, he would fade. The shadows didn't judge, but not because of any sort of feeling about judging in the first place. It just had better things to do, and more places to go -- more darkness to track down and destroy before the darkness would unleash itself fully and do more damage to others.
Without a word or even a moment's thought, it was gone and away on another job. It would always have work to do, and since shadows never sleep, it had no reason to wait in between.