The head maintains a constant internal temperature of 96°F. Although minimal electric activity occurs within the brain, these random activations are not indicative of any kind of conscious activity. Blood drips from its neck at a rate of one drop every two to eight seconds; all stains disappear within six to eight minutes. Rotation is observed in 2.8% of individuals, with one revolution every two to ten seconds.

The lume and its severed head seem to behave as a single unit. The stranger cannot survive without it, and dies when the head is destroyed, drowned, or moved more than ten feet from the lume's body. The head can be plucked from the air with little difficulty, and, as long as it stays within range of the body, can be released to float by its side once more. Unlike the stranger's body, the head does not appear to have any^ლ regenerative ability.

The lume is generated by bloodshed, physical cruelty, or other forms of destructive assault upon the human body, and appears in places^㇉ that have witnessed such violence, up to 1.1 years after the incident has taken place.^ʭ Car accidents and murders are two of the most common inciting events, but the site of any violent action can generate a lume under the right^Ԣ circumstances.

When the lume first appears, it is a small, undulating mass of flesh and arms, which squirm upward in a twisting rise to form the stranger's body, a process that takes only a few seconds. The ubiquitous severed head, meanwhile, generates within the stranger's flesh, starting off as a bead-sized, teratoma lump of hair and cartilege that expands in heartbeat-like throbs in a process lasting anywhere from two minutes to one hour. Upon the head's completion, it emerges from the back of the lume's body, leaving no hole behind.

The lume appears on its own 66.5% of the time, and in groups 33.5% of the time. It tends to appear around others of its strain, and thus, infestations grow in clusters within a city. Total populations tend to hit a maximum level of one hundred to two hundred individuals, however, thus preventing indefinite growth.

The lume possesses a dim-witted and unsubtle nature, and moves with clumsy, shambling motions. Although it does not appear to possess vision, it can react to sound, moisture, and temperatures, and thus avoids potential dangers in its vicinity. Its attention is focused only towards violent or destructive activity nearby; any other roaming seems entirely random. Although it does not engage in social actions, bands tend to form as individuals seek out and move towards the same extreme^Ꝍ events, and disperse when not in pursuit of a goal.

The lume is never aggressive towards a healthy sensitive, and in fact, ignores their presence and actions altogether. Instead, it is specifically drawn to sensitives who have suffered injuries as a result of assault, accident,^Ɠ self-harm, or other acts of violence.

Once it has found an injured victim, the lume attacks with unwieldy, but persistent hostility. Although possessing relatively minimal strength, encounters can quickly prove fatal as the stranger strangles and smothers its weakened victim. It is similarly aggressive towards corpses, attempting to suffocate^Э them using similar methods.