Apostle is the name given to various lifeforms originating from Mania. Apostles are a manifestation of spiritual energy that is scattered when humans die, pulled together into new forms by the strong emotional forces of collective human subconsciousness (Mantis Mirage Phase 3). Different forms of Apostle are the results of different human concepts and emotions. In their natural state, Apostles have no stable form. Their physical bodies collapse and reappear unpredictably, which is said to be due to some "fundamental flaw" in their existence. The Mantis Queen stated that the reason for Apostles' unstable forms is that the human heart is contradictory and unpredictable. It also claims that they need some certain humans who possess strong spirits, possibly referring to Sinners (Hunting Shade 4, "Nest"). Often times, the Apostle will inherit some or all of their "reference's" desires, which in turn influences the form they take. Mantis believed that, due to Apostles' human origin, it might be possible to awaken their humanity and communicate with them.
Early in their life cycle, Apostles lack intelligence beyond basic instincts, requiring human consciousness to develop a higher degree of sentience. While it is unclear whether they can survive without humanity, all Apostles appear to crave human consciousness, requiring it as a reference point around which to solidify their existence. Thus, the Apostles that are most likely to survive long-term are those that provoke the strongest reactions through fear and despair. Apostles also engage in mutual predation. Unlike Great Existences that consume each other for power, however, it appears that Apostles do so purely to eliminate competition and ensure their own survival.
The hallmark of Apostles as a "species", and the criteria that the Ring Research Institute uses to distinguish them from ordinary Corruptors, is an instinctive desire to enter BR-000 and reach the Perishing Star at its center. This impulse grows stronger the closer an Apostle is to DisSea, and ultimately can override an Apostle's other characteristic behaviors, as Du Ruo observed when the Sun Crow attacked DisCity. It seems that Apostles instinctively understand that, for unknown reasons, contact with the Perishing Star would "solidify" their existence in the physical world.
Corpus
(see Corpus for more)//
Corpuses have been shown to utilize a specific "host" around which to materialize and form a Corpseborne, with the host's desire being the necessary emotional trigger to transform the condensing Mania into a Black Ring. Although Corpuses seem to be stable existences that can persist without depending on human psychic energy, as fellow Mania-based creatures, they display similar attachment to and adoption of the emotional impressions of nearby humans.
Apostles of Ash
The Apostles of Ash are monstrous figures that exist within the Tide of Ashes, and are the most commonly encountered type of Apostle by the people of DisCity. Many Apostles of Ash appear to be enormous humanoids, but others (such as the ones fought in the Tide of Ashes events) are elemental-like monsters, and some (like Stella), resemble animals. Stargazer notes that they are attracted and driven by fear, suggesting that at least the humanoid Apostles may be a manifestation of human fear.
When Marguerite Nash first encountered the Apostles, a mysterious voice told her to "Return the Corpus to completeness."
Resonance
(see Resonance for more)//
The reflective property of Apostles is likewise exhibited by Mania itself. As Maniacs come into contact with uncontaminated individuals, their Mania, influenced by nearby consciousnesses, can spread from person to person like an airborne illness. This has been shown to happen especially during situations with large crowds under intense distress, where collective hysteria results in immense M-Value spikes.
Mantises
Among the earliest sighted in the Nightfall era, these Apostles are a manifestation of the human desire to be part of a group and adopted a eusocial insect-like form as a means of mirroring human social structure, observing the importance that companionship and community had on human development. Upon abducting Marguerite, the growing Mantis colony gained the Mantis Queen, who utilized her strong desire to understand and communicate with the Apostles as a means of continuing their species' evolution.
Unlike Apostles of Ash that constantly move toward the perishing star, Mantises stay on the outskirts of the forbidden zone and occasionally leave DisSea to prey on humans. As a relatively weak form of Apostle, Mantises are unable to go deeper into the forbidden zone and face stronger threats. For this reason, unlike other Apostles, they actively seek out and attack humans as a substitute for the Perishing Star. This also has the side effect of improving their emotional intelligence and causing them to imitate humans. (Hunting Shade 3 "Camp")
Immortal Libram
Outwardly, Sinners of the Immortal Libram tow the line between Sinner and Corruptor, with heavily mutated forms and severely eroded mental states. However, unlike with Corruptors, whose consciousnesses are entirely beyond repair, the Chief discovers through dreamwalking that their original selves have been preserved in order to perpetuate the existence of a kind parasitic Manic entity. These entities thrive on their hosts' stalwart determination in the face of overwhelming adversity, growing particularly powerful due to the conditions of the Keylan Expedition.