They are hostile spirits of the dead trapped in the 'twilight zone' between life and afterlife. These creatures can be repelled by the chanting of mantras. One can free them from their ghostly existence by performing their funerary rites. Being unaffected by the laws of space and time, they have an uncanny knowledge about the past, present, and future and a deep insight into human nature. Therefore many sorcerers seek to capture them and turn them into slaves.

Other legends describe them as the sons of either Krodha (figuratively "Anger") or as Dakṣa’s daughter Pishacha. They have been described as having bulging veins and protruding red eyes. They are believed to have their own languages, known as Paiśāci.

According to one legend, they are sons of Kashyapa and Krodhavasa, one of the daughters of Prajapati Daksha. The Nilamata Purana of the 7th century says the valley of Kashmir was inhabited by two tribes: the Nagas and the Pishachas.

Pishachas like darkness and traditionally are depicted as haunting cremation grounds along with other monsters like bhutas and vetālas. Pishachas are supposed to possess the ability to shapeshift and assume any form at will, and may also become invisible. They also feed on human energy. Sometimes, they possess human beings and alter their thoughts, and the victims are afflicted with a variety of maladies and abnormalities like insanity. Certain mantras are supposed to cure such afflicted persons and drive away the pishacha possessing that particular human being. In order to keep the pishacha away, they are given their share of offerings during certain religious functions and festivals.

Pāṇini, in his Aṣṭādhyāyi, described the pishacha as a "warrior clan".^{[This quote needs a citation]} In the ancient literature, the Dardic people in the north of Kashmir were referred to as "Pishacha" and Dardic languages were called Paiśāci. They are said to have been descendants of Prajāpati Kaśyapa.

Vampiric entities have been recorded in cultures around the world; the term vampire was popularized in Western Europe after reports of an 18th-century mass hysteria of a pre-existing folk belief in Southeastern and Eastern Europe that in some cases resulted in corpses being staked and people being accused of vampirism.^{[citation needed]} Local variants in Southeastern Europe were also known by different names, such as shtriga in Albania, vrykolakas in Greece and strigoiin Romania, cognate to Italian strega, meaning 'witch'.

In popular culture, it is commonly represented as hopping or leaping. In folkloric accounts, however, it is more formidable, capable of giving chase by running, and if sufficiently ancient or if it has absorbed sufficient yang energy, capable also of flight. According to folkloric understandings, "jiāngshī” came from the hills, soaring through the air, to devour the infants of the people".

In both popular culture and folklore, it is either represented as anthropophagous (i.e. man-eating), therefore resembling Slavic vampires, or as killing living creatures by absorbing their qi, or "life force".^[3] It is usually not represented as blood-sucking, as in the West European conception. During the day, it rests in a coffin or hides in dark places such as caves and forests.^[4]

De Groot suggests that the belief in jiangshi was the result of the natural horror at the sight of dead bodies, nourished by the presence of unburied corpses in the imperial China, which "studded the landscape", the idea of the vital energy flowing through the universe as capable of animating objects - including exposed corpses, and by severe cultural taboos concerning postponement of burial. These fears are described as having preoccupied "credulous and superstitious minds in Amoy".

The handprints visually capture the hidden threat and unknown fear associated with BTs. They are normally invisible and can only be sensed through special equipment or abilities (like Sam's BB unit). The appearance of handprints signals that BTs are nearby, a warning of their approach and the potential danger they bring.