The Contraproprioceptive Virus (CPV) is a tailored virus designed to crash a specific cladist on the System. For most of the System's history, it was the primary method of killing individuals sys-side. Viral constructs are often knives, syringes, or other menacing objects.[1] In order for an instance to be affected, the construct must instill an anticipation of danger and cause some kind of injury. Poisons and benign objects are inadequate because they do not draw a self-evident connection between the viral construct and the victim; the symbolism of killing is the vector by which CPV afflicts an instance.
An instance who afflicted with CPV suffers an unravelling of their sensorium, subjecting them to alien and inhumane sensations that very often coerce the instance to quit. Those who endure will eventually crash as a consequence of CPV, and the resulting core dump is seldom recoverable. Particularly savvy victims may manage to fork away the virus, although they would have only seconds to do so and a great deal of agony to grit their teeth against and will likely suffer long-term instability regardless.
The means to create viral constructs is a closely-guarded secret, and CPV is rarely used. After the Century Attack, the bug that enabled CPV to function was removed, rendering all viral constructs inert. On the Perils of Memory made it known to the public, and most cladists will recognize it when they see it. Crashing as a result of CPV is not a subtle affair; the afflicted instance dissolves into voxels as their avatar is corrupted by their unravelling sense of self. Most victims scream through the entire ordeal, their voices increasingly distorted until they finally quit or crash. Witnessing the use of CPV is as traumatic as witnessing a brutal murder because one has witnessed a brutal murder.