Mania is a disease-like mutation that causes abnormal transformations in humans by spreading physical and mental contamination. Maniacs, those infected with Mania, gain superhuman strength and endurance, but suffer from irreversible mental breakdown until they finally mutate into monstrous Corruptors. Officially, the cause of Mania is unknown, but it is widely believed in DisCity that Sinners are the source of Mania. In reality, Mania originates in a parallel dimension referred to as the Deep Mania, and is the vector by which spiritual energy is able to cross the boundary into the physical world. It is this process of cross-dimensional travel that creates contamination; Mania itself has no inherent corrupting properties beyond forcing this process to occur. Mania is able to enter the physical world only through Black Rings, but once present in the world, it can continue to propagate and spread under its own energy. Any person infected with Mania spreads it more and more as they approach transformation into a Corruptor; their tissues, secretions, voices, scents, and even presence are all possible triggers, and even the dead bodies of a Maniac can spread Mania, but the "burst" that comes as they transform is the main cause for the escalation of the plague.
The DisSea Explosion in N.F. 84 is the first officially traceable Mania incident (2-8), and the Mania plague was first discovered in DisCity in the aftermath of that disaster. However, Mania had actually first arrived in the physical world nearly a century earlier, during the cataclysmic meteor strike known as Nightfall. After the impact of the Perishing Star, the world was plagued by Mania calamities which ultimately destroyed the fabric of preexisting nations and societies and ushered in the new world order of the Nightfall era (5-9).
The severity of one's Mania (sometimes also referred to as "Syndrome M") is measured by a metric called "M-Value", which was developed by Banyan Medical College. Further investigation by the Ring Research Institute developed a property called the Keylan Constant, which states that if an individual's M-value is higher than a Base Value (represented by q), it will increase significantly over time, but if the M-value remains lower than q, it will stay stable over time. An individual with an M-value greater than q is considered a Maniac. Normal humans can't endure an M-Value above 200, and 98.4% of individuals who reach that point become Corruptors. However, some are able to remain human far beyond that threshold; these individuals, known as Sinners, possess an M-Value of at least 600 and gain powerful supernatural abilities. Nevertheless, triggers can worsen their Mania, which brings stronger power but also deeper mental contamination. Physical trauma can also affect one's mental state, making it more difficult to resist mental contamination (5-9). Eventually, Sinners' M-Values rise high enough that they break down like any Maniac, a process which may be referred to as becoming "Deteriorated". This threshold seems to be different depending on the individual's mental fortitude, as the Gray-Haired Girl's M-Value rising to the 1630s was cause for serious medical alarm, but Anne's M-Value exceeded 2131 with only minor symptoms. The reasons why some people are capable of becoming Sinners is also unknown.
Mania as a disease appears to be unique to humans, but its corrupting power can also seemingly affect physical locations and areas, which can have their own ambient M-Value as well. Mania contamination in physical spaces is associated with black goo and solid, twisting spikes that spawn nightmarish monsters.
Sources of Mania are also known to sometimes interact with and catalyze changes in one another through a process called Resonance. This term also sometimes refers to a phenomenon wherein those infected with Mania turn into a "thin consciousness field" after death, like an echo or a mirage, which often retains a final obsession or memory.
Symptoms
Symptoms of first-stage Mania include obsessive behavior, hysteria, paranoia, not eating or drinking for multiple days, addiction to certain behaviors, insatiable appetites for sensual pleasures, and extreme mood swings and hallucinations. At later stages, Maniacs become increasingly aggressive and irrational, losing any sense of self-preservation.
Anne's notes state that at M-Value 128, a patient started to lose his memory and his muscles changed enough that he accidentally broke her rib. At M-Value 200, normal humans transform into Corruptors.
Critical M-values are often reflected in physical changes, such as developing dark spots on the skin. Black smoke emanating from a Sinner's or Maniac's eyes, mouth, or wounds is a sign of total mental breakdown, indicating that the Maniac will soon mutate into a Corruptor. A Maniac nearing this point may no longer bleed, instead oozing black sludge from their wounds.
Treatment
Mania cannot be reversed, but it can be treated. In order to fight Mania, one must have an extremely rational mind, as losing control of one's emotions invites contamination; this understanding is core to the philosophies of Paradeisos and the FAC. Dr. Iron of SALVA Hospital has developed a method to treat first-stage Mania with a 71% success rate (DeadLover Radio). The details of this treatment are not known, but it seems to involve amputation of infected body parts.
The Shackles are the only known method of reducing one's M-Value. but they are effective only on Sinners, not regular Maniacs. Hypercubes also possess powerful anti-Mania properties, and are frequently used to clean up contamination, reduce the mental strain caused by exposure to it, ward off Mania-based monsters, and protect against the risk of elevated M-Values.
Contamination
The presence of intense sources of Mania like a Corpus begets contamination, both mental and physical. The Deterioration of a Sinner also spreads contamination in the area around them in a one-time burst. Mania contamination in physical spaces is associated with black goo and solid, twisting spikes that spawn nightmarish monsters. Simply existing in a corrupted space does not seem to risk infecting one with Mania, but as such places are often centered around a major source of mental contamination, they are usually dangerous for one's M-Value to enter. The ultimate form of this is a Black Ring.
Contamination can be psychically sensed by Sinners when they are near to it; the Chief appears to be more sensitive to it and able to detect it from greater distances. It is not known whether normal humans also possess the ability to sense contamination at any distance or intensity. To those who can sense it, contamination may "resonate" in such a way that identifies its source. For example, Hecate is able to tell the difference between the contamination caused by Mania crystals extracted from Ninety-Nine and that produced by the Inheritance (Unclaimed Crypt). M-values can also be measured with meter devices à la a Geiger counter (Night of Wonder).
High levels of contamination in an area may lead to space-time distortion, causing time to pass at different rates inside and outside the area and preventing any form of communication from passing in or out.
Mania Crystals
Mania crystals are a rare commodity that are created when Ring substance absorbs a Sinner's spiritual energy and can be obtained by extracting them from the bodies of individuals infected with Mania. High-grade Mania crystals are obtained from the bodies of Sinners, while high yields of low-grade crystals are refined from the remains of the many Corruptors in the Rust. While it may be possible for this to happen naturally, most Mania crystals are intentionally created by experimentation on Sinners by The Laboratory of PARMA. Crystals can be found in solid or liquid versions. The liquid can be injected to rapidly induce Mania and mutation, granting a normal human the power of the Sinner whose energy was used in creating the crystal. Thus, Mania crystals are frequently fought over by the gangs that crave this power. The solid version are embedded in other objects to create Mania weapons.
Mania crystals seem to have additional properties that can be activated by contamination like that of the Inheritance. They appear to be unstable, able to explode into physical corruption and give birth to monsters, including phantom versions of the Sinner that they were extracted from (3-12). Mania crystals embedded in a Corruptor also allow the Corruptor to be controlled by the will of the Inheritance (4-4).
Mania Weapons
A Syndican specialty, Mania weapons are made by embedding normal weapons with Mania crystals, used by the gangs to imitate the power of Sinners. Mania weapons can vary from the simple staffs of Thou Voodoos to the heavy guns of the Red Falcons, and their abilities vary depending on the ability of the Sinner that their crystals were extracted from. The most common source of crystals for Mania weapons is those from Ninety-Nine (although ones originating from Hella have also been seen), extracted and then sold by PARMA. When one uses a Mania weapon, their own mental activity is amplified as well, meaning that the more Manic they are, the stronger the Mania weapon's effect. Despite that, the weapons do not cause severe mental contamination in the users, as all the contamination the crystals generate is instead transferred to the victim.
Smuggling Mania weapons is a major source of illegal activity in Syndicate, and is used by Parma as a way to incite chaos in the district. However in Bai Yi's Interrogation, set after BR-004, the Chief notes that the amount of Mania weapons in circulation has dramatically decreased in recent months. Mania weapons have also been seen wielded by desert bandits in WhiteSands.
Mania Sorcery
Some Mania-infected individuals, whether Sinners or normal humans, are capable of manipulating Mania through a process known as Sorcery. Very little about this process is known. Sorceries mostly seem to be concerned with the channeling of spiritual energy towards or away from a target, such as to protect people or locations from contamination or to provide sustenance for a Corpus. However, other forms of sorcery have also been observed, including Segal's sorcery to conceal the location of The Garden; the creation of xenobodies and the ability they possess to conjure black flames are also likely forms of Mania Sorcery.
In DisCity, sorcery is mainly associated with the Underground. However, some Eastian seers are also capable of using sorcery. Eastian sorceries are characterized by more defensive/protective effects, and are represented by green light rather than the Underground's characteristic black and red.