The coldroni (/ˈkoʊldroʊni/) is a long, white and blue, lizard-like stranger with narrow eye markings and a tubular body. Its skin is frigid to the touch, and its blue inner flesh remains slick and oily even in sub-zero temperatures. Accumulation of frost on its surface is typical. The coldroni's lips, gums, and small, evenly spaced teeth are all blue, with the shade ranging from Egyptian blue to almost white in some individuals. Its body cavity contains compacted intestines, the color of which, like its teeth, varies between individuals. Although the coldroni does have a fully-formed mouth, it does not appear capable of opening its jaws under any circumstances, a potentially beneficial trait due to the fact that this mouth connects directly with its internal cavity, which lacks a tongue, throat, or any other differentiated oral tissues.
The coldroni's thick skin causes it to resist attacks and natural wear-and-tear, and although its regenerative ability is extremely slow (with the coldroni requiring several months of dormancy to recover from a deep cut), it is not non-existent.
The coldroni appears in sub-zero environments. Despite its increased prevalence during winter months and tendency towards frigid outdoor areas, it is also prone to generate in skating rinks, meat lockers, and any other artificially freezing environment.
The coldroni grows from a small, thin form, which lengthens and increases in bulk over the course of several days. The coldroni is vulnerable to changes in temperature during this time, and melts away to nothing when its environment is warmed to temperatures above freezing before it reaches maturity.
The coldroni's initial size is based upon temperatures during formation. Coldroni that develop in temperatures of 10°F, for example, grow to about three feet long, while coldroni that develop in temperatures of -40°F are capable of reaching lengths of up to 30 feet. Those individuals which reach maturity in temperatures of between 30-32°F do not grow very large at all, and retain a slender, neotenic form. These stunted coldroni move quicker and present some level of annoyance to larger, mature coldroni, which crush them when they get too close.
The coldroni possesses a cold disposition, and displays surly indifference to its surroundings. It is apathetic towards or distrustful of most stimuli, and generally avoids loud sounds or fast-moving objects, from which it stalks away at a slow, leisurely pace. It spends its life either on the move towards colder temperatures, or at rest once it has reached the coldest point within its environment. It often settles in freezer rooms, on the surface of frozen pools or ponds, or against the windswept sides of buildings, where it lays without moving, its eye markings staring outward, but its attention disengaged. The coldroni is also attracted to abandoned refrigerators, and, once it has found one, often curls up inside or around it for several hours before continuing on.
Just as the coldroni seeks out cold, so too does it avoid heat, taking wide paths around radiators, fire, and sunny expanses. Smaller individuals even display an aversion to human body heat and the heat radiated from electronics or combustion engines.
The coldroni's internal body temperature ranges anywhere from -58°F in smaller coldroni to as low as -140°F in the largest individuals. It freezes solid in external temperatures of below -147.6°F, but displays no ill effects once thawed out again. This change is sudden, and occurs only at that specific temperature – a coldroni in an environment of 146°F, for example, does not display partial freezing. The coldroni is unaffected by water, although it quickly freezes all water it comes in contact with. If submerged in a body of water, for example, the water around the coldroni freezes to encase its body in solid ice.
Just as its initial size is contingent upon conditions during generation, so too does the coldroni continue to grow and shrink throughout its life based on ambient temperatures. Low external temperatures cause the coldroni to grow larger in size, colder in internal temperature, and more sluggish in its movements, while high external temperatures have the opposite effect.
Due to the strain's heat-averse behaviours, the coldroni has a general tendency to grow larger over time. This rate of growth is almost imperceptibly minute, however, and is only observable over the span of several weeks, with significant growth taking months to achieve.
Aside from the perturbation that the largest individuals show to the smallest members of the strain, and any social behaviour – beyond sullen half-aggression – remains unobserved.
The coldroni's presence causes sensitives to experience a sudden drop in body temperature, akin to being placed into temperatures of 0ºF or lower (in the case of larger individuals). This effect occurs regardless of how well-bundled the sensitive is, and grows more severe over time. Frostbite sets in after 20-46 minutes of exposure, and death from heat loss occurs after several hours.
The coldroni itself displays no interest in sensitives beyond a vague annoyance, and tends to avoid them. Even when attacked, the coldroni remains non-violent, and either ignores attacks (in the case of the largest individuals) or moves away with an unsettled frustration. Although the coldroni cannot normally be set aflame, all coldroni lose mass gradually when exposed to fire, although the associated symptoms differ per the individual. Approximately 33% display a shriveling of the skin, 32% adopt increasing bodily rictus, and 35% exhibit an excessive shedding of water from their surface. Any decrease in size, however, is still quite slow, requiring several hours of constant exposure to fire to cause any noticeable loss in mass. Large coldroni, in particular, can only reliably be destroyed with the aid of gasoline or other flammable substances.
As it ages, the coldroni requires colder and colder temperatures in order to maintain its size. Its roam grows wider and more resolute in its pursuit of freezing temperatures (with limited rest or wandering). Eventually, an aging coldroni grows so desperate for unattainable frigidity that it hurls itself into icy water, or covers itself with snow in a futile but desperate attempt to stop its loss in mass. Ultimately, however, all coldroni shrink away to nothing, leaving behind only a small, shallow puddle of potable water.