The varidroli /ˈvɛərɪdroʊli/ is a long, black strain whose head and tail feel putty-like, while the dark parts of its body are cold and smoke-like in terms of physical sensation. Its eye markings are smooth and hard, and its odor is tarry and artificial, with younger varidroli possessing a stronger smell.

When stroked or tapped, the varidroli's head is perceived as solid. It cannot be cut or struck with force; breaking apart and dissipating. (Goodbye.) The smoky body, though white and appearing solid towards the tail, remains gaseous and invulnerable to harm. To the touch, the illusion of solidity pushes and parts against the hand, but cannot be gripped.

Its voice is calm, breathy, and even in pitch. It speaks using broken variants of phrases uttered within its territory.

The varidroli appears in any building containing ventilation ducts and air shafts. It tends to favor vacant (but not abandoned) locations, but does appear in occupied offices or other facilities should no more suitable environment present itself. White or grey walls, blue-tinted outdoor lights, and pipe-lined stairwells all work in it's generation's favor.

The varidroli starts off as a foggy mass – its form evident, but immaterial. During its first week of life, it clings to the surface near which it appeared as its head solidifies, nose-tip first, before stopping just above the stranger's "neck". Once mature, it detatches from its clutch and begins to explore its territory.

The varidroli keeps its disposition restrained, its instincts curtailed as it remains vigilant in its inspection of its territory. It drifts, low to the ground, and with its grip on nearby objects as though guiding itself, though such steadying does not seem strictly necessary. Most stimulus draws only the occasional minimal response, with much of the stranger's attention remaining fixated on the minutiae of its environment – the seams between the vents and walls, small dings and stains upon the floor, or the ridges of drop ceiling panels. Though it will avoid overt activity, retreating to the safety and seclusion of its vents, it does so with minimal response, its composure constant in its evenness.

The varidroli cannot move more than two hundred and twenty-nine feet from its point of generation, except though ventilation ducts. It does not act as though obstructed by barriers; rather, it turns with disinterest upon reaching its bounds, and with its head held level, continues on another route.

Despite the stranger's blank outer demeanor, it leads an active life inside its den. It curls, it uncurls – it places its hand on the ceiling and tangles itself into its own body, like a small child at play.

Curiosity towards sensitives is not exhibited readily, but cannot be claimed as absent, with the varidroli drifting in a slow circle around calm-tempered intruders. It does not tolerate handling, and when cornered, grows agitated and defends itself using its mesmeric effect.^𐊭

The incapacitated^ụ sensitive, however, does hold the varidroli's interest. The stranger grows calm and vaguely inquisitive once more, looming over the gasping and struggling body.

Once gasping ceases, such interest fades, leaving the contorted, open-mouthed body behind.

During the final fifth to third of the varidroli's life, its head begins to "recede" towards the nose, mask-rind fading away into a white-but-quickly blackarianted mist. A secondary set of eye markings appears beneath where the skin of the "incipariated alamask head" had been, and the edges of the body grow more fuzzy, which does nothing to affect its demeanor.

By the time the nose-tip disappears, the edges cannot be seen at all; and so the blurry death goes unmarked, the space odorless within the week and no corpse, no corpse, no corpse.