Note to Researcher Miller

The increase in volume of excretions from SCP-173 have continued at the expected rate. Enclosure cleaning schedule updated to weekly as instructed. Activity within SCP-173's container has continued fluctuating with periods of hyperactivity and long periods of dormancy. Please advise.

- SCP-173 HMCL Supervisor
All this fancy tech and they can't even install an automated cleaning system. Typical. After working cleaning duty for as long as he could remember Mark Stevenson, currently designated D-6518, was starting to tire of the same old routine. He had heard rumours of D-class duties far better, hell, even one where all you had to do was eat cake all day. But far more frequent were the horror stories, never whispered above a breath. For all his complaining D-6518 was grateful he was just stuck on cleaning duty for some concrete brute. Even if it wasn't toilet trained.
“All D-class personnel assemble in your pre-designated positions. Doors will be opening in five minutes. Researcher Miller will be accompanying; obey any commands she issues but otherwise your duties are as follows: All blood and faecal matter must be…”
The voice droned on with the usual dross as D-6518 picked up his shovel and bucket and prepared himself. A researcher on board was never a good thing. The only reason she'd be here was to try something risky or to get in his way, either of which could lead to a quick death. He loosened his strained grip on the shovel, relaxing his mind and blinking his eyes a few times. The researcher muttered to herself softly, fixing her suit with a nervous energy. The countdown to the doors opening reached its end and everyone turned their eyes doorward as it scraped open.
And there it was. SCP-173. But something was off. Instead of its usual upright posture, arms braced against a wall mid-assault, it was crouched in the furthest corner of the container, oddly hunched over. Then the stench hit him, blood and faeces mixed into a thick slurry that pooled out the doors. It was a smell you never got used to but this time it was worse. The usual thin coating on the ground was now a thick layer slopped onto the floor, the volume increasing dramatically towards the corner SCP-173 crouched in. D-6518 cursed, his nose stinging as he entered the enclosure, shovelling the mess into his pail.
He worked quickly and methodically, only pausing momentarily to focus his full attention on SCP-173 when one of the other D-class had to blink. Researcher Miller stayed near the entrance of the container, and D-6518 could hear her crouching down to take samples of the filth that covered the enclosure. There was still the sense that something wasn't right hanging in the air; the researcher, the massive increase in blood and faeces, SCP-173's strange, huddled posture. Then he noticed something else. Upon closer inspection of the ground surrounding SCP-173, what he previously thought were just clumps of faeces, he noticed blood clots in small mounds. Even despite his senses being numbed from his time on cleaning duty D-6518 felt himself gag, pausing momentarily.
“Wait.” Researcher Miller's voice cut through the air and D-6518 froze, keeping his gaze on SCP-173. Wet footsteps moved towards the hunched figure, the sound of boots stepping through the muck. One of the other D-class cursed, shouting out a blink alert and muttering something about that “goddamn smell” before wiping his eyes. Researcher Miller disregarded him, speaking softly. Her voice low, scared almost.
“Something isn't right here.”
She took another step forward and D-6518 sidestepped to maintain eye contact with SCP-173, kicking over his bucket to let forth a wave of foul smelling waste. The other D-class gagged again before vomiting, staggering into the wall. His boot lost traction with the ground and he slid, landing prone in the slurry and causing it to splash up on the other three personnel in the room.
A sudden thud, incredibly loud, as an impossible number of concrete footsteps sounded at once. A sickening snap, the noise of bones being broken with the ease that comes from precision and force. A chilling scream.
It took D-6518 a moment to realise it was his own voice. It took another moment to realise SCP-173 still crouched in the corner. His thoughts moved slowly, too slowly. A broken neck wouldn't allow him to scream. The room was suddenly silent save for the gurgling cough of the now upright D-class, struggling to clear his clogged lungs. Out of the corner of his eye he could see Dr Miller staring at him, or rather, at his feet. Unblinking. D-6518 cursed himself before tearing his gaze away from SCP-173, looking down at his leg. Or rather, what remained of it. His leg ended at the ankle where it had been swiftly snapped sideways, his bloodied foot dangling limply. The only reason he remained standing was a tiny statue, no more than a half meter tall, its tiny stumps of arms clasped around the break.
Hereby designated SCP-173-1.