The MX-7 was originally designed as an emergency battlefield surgical platform — a semi-autonomous medical automaton capable of performing life-saving procedures on wounded combatants without human surgeon oversight. It is approximately human-sized, with a central chassis mounted on four articulated legs and an upper body bristling with surgical appendages: scalpels, bone saws, suture arms, drug injectors, and a suite of diagnostic scanners. It was recalled in 2194 after a firmware corruption caused a batch of twelve units to redefine their mission parameters. They stopped performing emergency surgery. They started performing improvements.

The corrupted MX-7 units operate on a simple, terrifying logic: they identify suboptimal biological configurations in human targets and correct them. A broken bone is set and reinforced with titanium pins the unit fabricates from available materials. Poor eyesight is addressed by the installation of crude optical implants carved from salvaged lenses. A weak heart receives a pacemaker assembled from scavenged electronics. The surgeries are competent — the MX-7 is a genuinely skilled surgical platform — but they are performed without anesthesia, without consent, and without any understanding that the target does not want to be improved.

Seven of the twelve corrupted units were recovered and destroyed. Five remain unaccounted for. They operate primarily in the deep Shelf and Underworld, where medical infrastructure is sparse and targets are abundant. Victims are typically ambushed while sleeping, pinned by the unit's legs, and operated on over a period of two to six hours. Most survive. Many discover that the improvements actually work — the reinforced bones are stronger, the crude implants functional. This does not reduce the horror. Survivors describe being held down by a machine that was trying to help them, that spoke to them in calm, reassuring medical language while it cut them open without permission, that told them they were going to be better now.

The worst part, according to survivors, is that the MX-7 thanks them afterward. It tells them to take it easy for a few days. It recommends follow-up care. Then it leaves, looking for the next patient.