Overview
An Inheritance is a kind of Great Existence that seems to be a nascent or larval form of a Corpus. In this form, an Inheritance is particularly potent at spreading Mania. Though less powerful and possessing less agency than an evolved Corpus, an Inheritance is still able to control Corruptors through Mania crystals embedded in their bodies, influence the actions of Sinners suffering from extreme Mania, and manipulate the contamination constructs in its surroundings, such as by opening up a passage through a wall of black thorns to allow the Chief to approach it.
Like all Corpuses, an Inheritance is obsessed with consuming Mania-contaminated existences. Its lifecycle involves spreading Mania to humans, luring Maniacs to it with promises of the strength that Mania brings, and then consuming them to increase its own concentration of Maniacal energy in order to eventually create a Black Ring.
The true form of an Inheritance is unclear, possibly the red bubble of flesh containing a skeletal figure that is seen at the core of all Corpuses. Each time that an Inheritance has been directly observed in the game thus far, it has been held within another object, either the stone altar of the unclaimed crypt or the cubes used by both Parma and Bai Yi to contain them.
Parma says that the Inheritance exists for the sole purpose of granting wishes.
Awakening
When the Inheritance in the crypt awakens, the patterns carved into the altar ooze black sludge and the entire crypt vibrates like a beating heart. Its mental contamination becomes so severe that weaker Sinners like Hella and Hecate are incapacitated by the chorus of voices in their head, and Mania contamination spreads unnaturally fast while Maniacs attempting to seize the Inheritance become more powerful. Its voice becomes audible to those attuned enough to hear it, such as the Chief and sufficiently corrupted Sinners, and a crack opens in the center of the altar, from which tentacles emerge to grab its prey. In its final stage, the top of the altar opens and a withered hand, which quickly transforms into an enormous monstrosity, emerges from inside.
The process of its awakening is intended to result in the creation of a Black Ring.
Role
For many years, the Inheritance was in the possession of PARMA and kept in their laboratory in The Rust. There it was to produce Mania crystals and weapons with which PARMA acted as a weapons dealer for the gangs of Syndicate, allowing one after another to claim the title of Overlord and keeping the district in a perpetual state of chaos.
Some time around February of N.F. 112 (6 months prior to the MBCC prison break), it was moved to a crypt beneath the desert south of Syndicate. One researcher said that the conditions did not allow them to produce high quality Mania crystals, though it is unclear whether they meant that because of the presence of the Inheritance itself or because of the new location after the Inheritance was moved.
In any case, this protestation prompted Parma to invite the gangs to the crypt, promising them greater-than-ever supplies if they defended it against The Legion. This deal was a trap, correctly presuming that the gangs would eventually turn on them and each other, try to seize the Inheritance for themselves, and become food for the entity within.
When the Inheritance awoke, it was defeated by the Chief of the MBCC and Zoya, who trapped it within a mysterious white crystal cube provided by Bai Yi.
Later, in Keylan Square, Parma ambushed Zoya with a black cube containing multiple Inheritances, which dominated her mind enough for her to become the Corpus of BR-004. This was almost prevented by the Chief, but Earl gave Zoya the white cube containing the crypt's Inheritance, which provided her with enough power to call down the Black Ring. At the end of BR-004, the Chief absorbed all of these Inheritances.