RPC-843 is the designation for a mass-produced, 2.3-meter-tall humanoid lined by a layer of black ceramic purpose made for abduction. It is composed of machinery and a genetically human organism. The head lacks features and a lower jaw, and it is capable of turning its neck 330 degrees. Its shoulders span 1.2 meters, which rise above its head at the clavicular joints. It possesses no identifiable internal organs other than a heart. Despite its lack of internal and sensory organs, it is capable of movement and sensing stimuli.
Its torso accommodates a watertight 1.1 cubic meter storage space that can be accessed through a double hatch connected to concealed muscles and extra ribs. The back functions as a glovewall, as RPC-843 possesses two extra arms that it can fully retract and conceal. The ceiling is lined with various vital sensors, as well as nozzles that release blood. The floor has drains that connect to the circulatory system. Its blood is breathable and contains traces of amnestics and ectoplasm.
A protrusion extends from its midback that is slitted and covered by vents. The slits release ectoplasm in bursts that immediately crystalize into the shape of avian wings that span 8 meters. RPC-843 can manipulate these wings to take off and fly at 86 km/h. RPC-843 can remove these wings at will in a process that causes them to emit light and continuously brighten until they shatter in an explosion.
RPC-843 is capable of becoming incorporeal, rendering it invisible but paradoxically remains to cast a shadow. If RPC-843 is in a direct line of sight and unobscured, it is incapable of becoming incorporeal. When exiting this state, black ether will fill into RPC-843's shape and become tangible, returning it to its original form. RPC-843 releases guttural, high-pitched screams when it uses this ability, with a voice that varies from model to model. If an observer prevents this, the scream will be cut abruptly.
RPC-843 displays extreme aggression and no signs of sapience. Its behavior is predatory and prioritizes those who are smaller, unarmed, and anomalous. It stalks targets while incorporeal on foot or in midair and will circle around them until an opportunity arises, such as a distraction. RPC-843 has been recorded waiting a month before attacking.
To initiate an attack, it will dive near a target and non-lethally overpower them in a grapple, disarming them if it recognizes a weapon. It will then pull them inside its chest space in tandem with its internal arms and push them into a fetal position. The hatches will then slam shut, lock, and the chest space will flood with its blood. After abducting a target, RPC-843 will then rush to leave the area and vanish.
Most individuals trapped inside RPC-843 lose consciousness within three minutes. Those who have remained conscious after 5 minutes have stated they could see through the body of RPC-843 and see something that resembles a human standing, floating in place above them. These figures have been seen panicking, weeping, writhing, and gazing back.
RPC-854 is able to sustain most injuries to its body due to ectoplasm crystalizing over its wounds, except for damage to its heart. In the event RPC-854's heart is ruptured, it will release a deafening screech as its flesh transforms into massive amounts of blood, bursting in every direction in an explosion. Individuals who were inside an RPC-854 instance at its time moments before its expiration claim to have been spoken to by it.