A causal scavenger and containment dossier for Cthulhu Eternal
Incident report C-15
The Harrow archive held forty-three boxes from the Bellweather manifestation. Most were useless. Investigators had collected plaster, clothing, damaged cameras, medical files, witness statements, architectural plans, and every object found within two metres of the emergence corner. Twenty-eight years later, nobody could say why the material was still classified, and the surviving index listed case numbers with no descriptions.
Archivist Lena Ortiz started reconstructing the collection on Monday. On Tuesday she found a pale animal inside Box 11, maybe forty centimetres from its narrow head to the end of its translucent abdomen. Ten jointed limbs moved across the papers without tearing them, and wherever the limbs passed, the ink stayed visible but stopped forming recognizable words. Ortiz sealed the room and photographed the animal. The photograph showed an empty table.
On Wednesday, the hospital denied ever treating the Bellweather casualties. Its files still held the admissions, surgeries, and pathology reports, and staff could read each document; nobody could explain why the records had been grouped under one incident number. On Thursday, three former investigators remembered working together. None remembered where they had met. The archive room reached 41 degrees Celsius despite a working cooling system. Magnetic media failed in adjacent rooms. Ortiz ran a fever and kept asking why her wedding photographs contained a woman she did not recognize. On Friday, the animal entered the photograph Ortiz had taken on Tuesday, and emerged in her house beside the camera.
By the time response personnel arrived, Ortiz remembered her wife, their home, and twelve years of marriage. She had lost every reason the relationship had begun. Her wife remembered meeting Ortiz while reporting on the Bellweather deaths, and that assignment had disappeared from the newspaper’s archive. The Cleaner was found under their bed, grooming black fibres from its mouthparts. The nearest untreated corner smelled of blue vapour.
The cleanest Hound attack leaves no case
A Tindalosian Cleaner consumes physical correlations left by angular manifestations. It feeds on the capacity of one record to explain, identify, or reconstruct another. A photograph can survive its attention with every pixel intact while losing the connection to its subject. A witness can keep every sentence of a testimony while becoming unable to recognize the event it describes. Two databases go on holding accurate records under identifiers that no longer join. The individual facts stay true and operationally useless as a history.
Cleaners usually turn up after a Hound has weakened or severed the strongest records anchoring it to curved time, when the remaining scent is diffuse: partial memories, unexplained injuries, damaged rooms, administrative links, copied files, and lives reorganized around the encounter. Cleaners graze through those remnants until the environment can no longer recover a coherent Hound history. Their feeding lets the Hound delocalize, and it can also protect surviving witnesses from renewed pursuit. The danger is in causal extent: a Hound encounter may have shaped decades of decisions and relationships, and the Cleaner follows those consequences wherever they lead.
Information has a body
Information in physics needs physical states. A bit can be a voltage, a magnetic orientation, a molecular configuration, a photon polarization, a neural connection, a mark on paper, any reliably distinguishable condition. Resetting a memory device from either logical state to one standard state is a logically irreversible operation; two distinguishable inputs converge on one output,
and the output no longer identifies the input. Landauer’s principle ties this loss of distinguishability to thermodynamics. For erasure of one unbiased bit in contact with a heat bath at temperature 
with 
Mutual information as food
Say two physical systems 
where 
The physical states of
Reversible computation and uncomputation
Charles Bennett showed that general computation can, in principle, be done reversibly. A reversible process keeps enough information to reconstruct its earlier state, and intermediate garbage can be removed through uncomputation: copy the useful output, then run the computation backward so the auxiliary states return to their initial condition. A simple conceptual pattern is
where 
Quantum erasure, carefully stated
Quantum-eraser experiments concern which-path information in controlled interference setups. Interference can reappear in appropriately sorted correlations once the distinguishing information is made unavailable in the relevant basis, and the experiment neither deletes a macroscopic past nor sends a controllable message backward through time. The useful idea for the Cleaner is narrower: distinguishability can depend on correlations and measurement basis rather than on visible damage to a record, so two intact systems can stop providing usable which-history information after their correlations are transformed. The leap from photons in an interferometer to human lives and archives belongs entirely to the Tindalosian fiction.
The Tindalosian axiom
A Cleaner can reversibly couple to the causal record of an angular encounter, transfer the relevant correlations into a protected digestive state, and export their entropy through angular degrees of freedom.
The process has three stages. In ingestion, the Cleaner correlates with a target record and removes its useful connection to the encounter, with the missing relationship still encoded inside the animal, so killing or forcing it to disgorge can restore the record. In uncomputation, the animal follows adjacent correlations toward the event or outward into its consequences, each consumed link supplying the information needed to identify the next physical state, which produces the appearance of movement along biography, provenance, or institutional dependency. In export, after digestion, the Cleaner resets its internal organs and pushes the entropy and correlation into angular space, and the erased relationship then has no recoverable curved-space copy known to human physics. Export is the impossible part. Landauer’s principle stays visible as waste heat and disorder because the Cleaner cannot route the entire thermodynamic cost through its angular body, so large meals warm rooms, disrupt electronics, denature tissue, and throw bursts of low-grade noise across nearby instruments.
Appearance
A Cleaner has a narrow segmented body between thirty centimetres and a metre long, its size set more by current digestive load than by age. The projected anatomy looks like several cleaning and indexing mechanisms forced into one animal: ten to fourteen fine grooming limbs ending in combs, brushes, or hooked cilia; a flattened head with paired mouthparts moving like tape through a read head; compound eyes patterned with fingerprint whorls and retinal blood vessels; a translucent abdomen holding scraps of handwriting, photographic grain, neural tissue, magnetic domains, and moving geometric scars; pale organs that pulse whenever two records are compared nearby; and a haze of warm air and broadband electronic noise around a well-fed specimen. Its feet leave no ordinary prints, and surfaces touched during feeding lose their indexing marks first: labels fade, timestamps corrupt, filenames detach from extensions, and witnesses forget proper nouns before they lose events. Cleaners can get disturbingly specific. After feeding extensively on one life, the arrangement of limbs starts to echo the subject’s posture, its eyes take their iris colour, and the abdominal segments pulse in the rhythm of their speech. That anatomy helps the animal address records encoded in the person’s habits and nervous system.
Ecology
Cleaners look like commensals or symbionts of Hounds. A Hound violently severs the strongest tethers holding its projection in curved time, and Cleaners remove the diffuse correlations that remain. The relationship may be wound cleaning. Hounds tolerate Cleaners near damaged tissue and sometimes expose blue membranes for grooming, and a Cleaner has been observed entering the open thorax of a dying Hound and emerging hours later with its abdomen full of faces, diagrams, and room numbers, the Hound delocalizing immediately afterward. Other organisms benefit too. Probability Reefs regain access to obscured branches when Cleaners eat the which-history records causing local bleaching. Palimpsest Hounds lose anatomy when a Cleaner removes the inference supporting an organ. Which-Way Men use captive Cleaners to sever links threatening one of their Paths. Corner Brood infestations get harder to reconstruct after a Cleaner consumes the building surveys and remediation records. Redshift Carrion follow the heat from large erasures. The Cleaner shows no loyalty to any species. It feeds wherever angular events have produced unusually dense, redundant causal structure.
Constructing the Record Graph
The GM represents the encounter with a Record Graph. Nodes are physical systems carrying recoverable information; edges are causal, interpretive, or copying relationships. Use eight to fifteen nodes for a normal operation, and give each node five properties.
| Property | Purpose |
|---|---|
| Record | The person, object, system, or consequence carrying information. |
| Content | What it establishes about the encounter. |
| Weight | How much recoverable information it carries, rated 1 to 3. |
| Edges | Other records it explains, identifies, produced, or copied. |
| Human value | What is lost if the record or connection is consumed. |
Example nodes:
| Record | Weight | Content | Important edges |
|---|---|---|---|
| Original witness | 3 | Direct memory of manifestation | Spouse, journal, scars, relocation |
| Journal | 2 | Description and chronology | Witness, investigator, archive |
| Spouse | 2 | Behavioural corroboration | Witness, relocation, child |
| Rounded house | 1 | Consequence of defensive action | Contractor, witness, photographs |
| Hospital file | 2 | Geometric injury and date | Scar, physician, archive |
| Adult child | 3 | Life downstream of escape | Parents, relocation, family records |
| Case index | 1 | Joins otherwise separate evidence | Every institutional record |
| Hound scar | 3 | Physical angular residue | Encounter site, photographs, Cleaner |
The graph should hold several possible feeding routes. At least one route has to reduce Scent without destroying every valued node, though that route can still demand an ugly sacrifice.
Record states
Each node and edge is in one of four states.
| State | Meaning |
|---|---|
| Recoverable | The record contributes normally to the Hound history. |
| Ingested | The Cleaner holds the correlation. It can still be restored. |
| Disconnected | The facts remain, but this edge no longer joins them. |
| Exported | The correlation has left recoverable curved space. Restoration needs another surviving copy. |
Mark edges separately from nodes. A Cleaner often eats an edge and leaves both connected records physically intact, which lets the GM describe precise losses instead of generic amnesia. At the end of each scene the Cleaner can rest, one Ingested item becomes Exported; choose the oldest or roll among equally old items. Export restores WP by Weight and produces the listed thermodynamic effect.
Information Weight and heat
Weight is the importance and redundancy of the consumed correlation in the scenario, not a literal count of microscopic bits.
| Weight | Typical record | Export effect |
|---|---|---|
| 1 | Label, isolated note, weak association | Room warms perceptibly; nearby electronics suffer brief noise. Cleaner restores 1 WP. |
| 2 | Durable testimony, medical file, relationship-forming memory | Local temperature rises 5 to 10 degrees Celsius; sensitive equipment fails; living witnesses lose 1D4 WP. Cleaner restores 1D4 WP. |
| 3 | Direct witness, redundant archive, identity-defining consequence | Heat and neurological disruption fill the area. Everyone nearby makes a CON test or takes 1D6 damage and 1D4 WP loss. Cleaner restores 1D6 WP. |
Rapid export of several Weight 3 records can cause a Thermodynamic Purge, resolved as Lethality 10% within the affected building or networked facility, with survivors taking the sum of the percentile dice. The form should follow the storage medium: fire in paper archives, induced currents around magnetic storage, fever and seizure in neural tissue, pressure and chemical disorder in biological samples.
Feeding procedure
Each feeding action runs in five steps. First, select an accessible record; the Cleaner has to occupy its location or reach it through Backward Foraging. Second, identify an edge or node, stating exactly which relationship or record is threatened. Third, resolve resistance: unattended objects offer none, a conscious witness may resist with an opposed POW test, protected systems may use an appropriate skill or security rating. Fourth, apply the loss, marking the target Ingested or Disconnected and describing the specific practical consequence. Fifth, expose the next route, revealing which adjacent records the Cleaner can now sense. A failed resistance roll should never erase an undefined portion of a character; name the memory, relationship, skill context, index, or causal link before the dice hit the table.
Guiding a Cleaner
Protagonists can steer its feeding path through real correlation engineering. Sacrificial copies: make a compact, authentic record holding correlations the group can afford to lose, remembering that a simple forgery provides no nutrition and the copy has to derive physically from genuine evidence; a successful Computer Science, SIGINT, Forensics, Science, Art, Psychotherapy, or relevant test builds a Weight 1 or 2 lure, a critical includes one chosen edge, a failure builds the lure but exposes an unintended adjacent record, and a fumble leads the Cleaner straight to the source. Edge isolation: separate records from the indexes, calibration data, witnesses, and metadata that make their relationship recoverable, starving a route without destroying the underlying facts. Controlled comparison: present two selected records together, so their high mutual information draws the Cleaner to the edge between them; it is the safest way to choose what it eats and the fastest way to make it aware of both endpoints. Thermal tracking: erasure makes heat and noise, so infrared cameras, power monitoring, magnetic sensors, network error rates, and medical telemetry can pick out a feeding event and reveal where the Cleaner has been, often after the corresponding labels have already lost meaning. Digestive interruption: stun, cool, restrain, or anaesthetize the Cleaner before export, each success delaying digestion for one scene, though repeated interruption makes the animal desperate and can trigger Defensive Unindexing.
Tindalosian Cleaner
Angular causal scavenger
Roll each specimen or use the typical column.
| Characteristic | Roll | Typical |
|---|---|---|
| STR | 2D6+1 | 8 |
| CON | 2D6+7 | 14 |
| DEX | 4D6+4 | 18 |
| INT | 3D6+2 | 12 |
| POW | 4D6+4 | 18 |
| HP | (STR+CON)÷2 | 11 |
| WP | = POW | 18 |
Movement: 12 metres; Backward Foraging ignores spatial distance. Skills: Alertness 70%, Athletics 60%, Dodge 60%, Search 80%, Stealth 70%, Unarmed Combat 50%, Unnatural 50%. Armour: 2 points of flexible projected tissue. vs Lethal Damage: NORMAL.
SAN Loss: 0/1D4 to see a Cleaner feeding on an object; 1/1D6 to experience Index Consumption; 1D4/1D10 to watch an erased relationship return from a ruptured Digestive Archive.
Attacks
Grooming Limbs 50%, damage 1D6. Fine hooked limbs cut clothing, skin, cables, labels, and storage media. On a critical it also removes one minor physical identifier from the target.
Index Consumption 60%, opposed by POW, costs 2 WP. It consumes one named association from a conscious target: a face linked to a name, a location linked to a route, a procedure linked to its purpose, a memory linked to the person who shared it. The facts on either side survive. The target loses 1D6 WP and tests SAN at 1/1D6.
Defensive Unindexing 50%, opposed by POW, costs 3 WP. Everyone within 5 metres loses the ability to tell apart one declared category for 1D6 turns: ally from stranger, exit from entrance, weapon from tool, original record from copy. The category must relate to something the Cleaner has ingested. On a critical failure the effect lasts until the relevant Ingested item is restored or exported.
Powers
Causal Grazing. Feeding changes a node or edge on the Record Graph by the procedure above. A mundane attack cannot restore an Exported relationship.
Backward Foraging. After consuming a record, it may spend 2 WP to emerge beside one physically existing adjacent node regardless of distance, travelling through the correlation without crossing the space between. Isolation works only after the relevant edge has been severed.
Uncompute Injury. It spends 4 WP and feeds on a wound with a documented causal chain. Mark the wound and its supporting records Ingested and restore 1D6 HP to the subject. Memories, scars, medical records, compensation, relationships, and adaptations caused by the injury become accessible feeding targets. Export makes the healing permanent if enough of the causal chain has been removed.
Digestive Archive. Every Ingested item stays encoded in the abdomen until export. Investigators can recover one item with a successful Surgery, Science, Unnatural, or specialized handling test after restraining the animal; failure makes it attack, and a fumble ruptures the archive.
Archive Rupture. At 0 HP, every Ingested item returns to its most compatible surviving physical carrier. Memories return, indexes reconnect, corrupted files regain metadata, and erased interpretations become legible. Each restored Weight 2 or 3 item raises the relevant Scent Track by 1, to a maximum of 6, and everyone affected tests SAN by the returned material.
Angular Export. At the end of a scene it exports one Ingested item, restores WP, and produces heat by Information Weight. Exported correlations leave no local copy inside the animal.
Scent Reduction. Whenever consumption severs every recoverable path from one major record to the originating Hound encounter, reduce Scent by 1. If no path remains from any present record to the encounter, Scent falls to 0 and the Hound can delocalize.
Killing one
Cleaners are physically fragile once cornered. Gunfire, blades, fire, and crushing force all work on their projected bodies. The tactical problem is the Digestive Archive. Killing a newly arrived Cleaner may restore only a few labels and memories. Killing one after a week of feeding can reconnect an entire institutional history in a single instant: witnesses live years of missing associations at once, backups recognize orphaned files, pattern-matching systems rebuild deleted cases, and Hounds get a sudden, concentrated tether. After export, killing the Cleaner cannot recover the consumed correlation, and its death may still leave the causal graph stranded in a partially erased state. Capture, controlled disgorgement, and guided feeding are usually safer than extermination.
What Cleaners want
Their behaviour reads as appetite, not abstract purpose. They prefer correlations with high redundancy, strong causal ancestry, and angular origin, so a well-indexed archive pulls them harder than a room of unrelated books, and a family shaped by one encounter offers more nutrition than a crowd of strangers. Cleaners avoid fresh Hound manifestations until the Hound has weakened. They approach injured Hounds submissively, grooming blue membranes and flinching from sudden movement, and they turn aggressive when kept from exporting a large meal. Intelligent specimens may bargain, offering memories or restored links from the Digestive Archive, though communication stays difficult, because every sustained exchange creates new correlations for the animal to taste.
Running the Cleaner fairly
Draw the Record Graph before play. Give every important node human value beyond its Scent contribution. Identify the threatened node or edge before resolving resistance. Keep Ingested material recoverable for at least one full scene. Show thermodynamic traces after every export. Reveal the next accessible nodes after feeding. Let authentic sacrificial records and controlled comparisons work. Make Archive Rupture restore only material still inside the Cleaner. Lower Scent when the players genuinely sever recoverable paths. And allow a careful plan to save the witness and release the Hound, provided the group accepts a meaningful loss elsewhere. The operation is graph surgery under pressure. Arbitrary amnesia destroys player agency and turns the creature into a narrative veto.
Operation: The Necessary Stranger
Situation. Dr. Miriam Vale survived a Hound manifestation in 1996. She escaped before making a formal account, went through an early Unremembering, and spent thirty years avoiding investigation. Her life still changed because of the encounter: she left her research post, moved across the country, married investigative journalist Rebecca Chen, and raised a daughter, Nora, and Rebecca had originally met Miriam while researching unexplained deaths around the abandoned laboratory. The Hound has never fully delocalized, its remaining Scent persisting through relationships and consequences rather than explicit testimony. A Cleaner has arrived to finish the work.
Starting Record Graph.
| Node | Weight | Content | Human value |
|---|---|---|---|
| Miriam’s inaccessible engram | 3 | Direct encounter | Her autobiographical continuity |
| Rebecca’s suppressed article | 2 | Deaths linked to laboratory | Her career and reason for meeting Miriam |
| Their marriage | 3 | Life created through investigation | Thirty years of shared identity |
| Nora | 3 | Downstream consequence of relocation | An independent person with her own life |
| Laboratory scar | 3 | Persistent angular residue | Current Hound anchor |
| Miriam’s resignation | 1 | Behavioural consequence | Career history and pension records |
| House renovations | 1 | Avoidance of sharp corners | Family home and contractor archive |
| Unremembering physician | 2 | Procedure and elicited account | Only trained operator who can help |
| Bellweather case index | 2 | Connects deaths, article, and laboratory | Institutional reconstruction route |
The Cleaner starts with the edge between Rebecca’s article and the case index Ingested. At the end of the first scene it will export that link.
Escalation. The Cleaner follows the graph by player actions. Protecting Miriam drives it toward Rebecca’s article and the marriage. Restoring Miriam’s memory draws it straight to the engram and raises Scent. Moving Nora exposes family records, medical files, and travel history as new edges. Investigating the laboratory strengthens the scar’s connection to every surviving node. Killing the Cleaner restores all Ingested links and raises Scent fast enough for a Hound manifestation. Allowing unrestricted feeding eventually reaches Nora, the largest living consequence of the escape.
Viable plans. Causal bypass: build a mundane, independently supported history in which Rebecca and Miriam could have met without the laboratory investigation, preserving the marriage and Nora while letting the original edge be consumed; the replacement history has to be physically realized through authentic relationships and records, and a fabricated scrapbook will fail. Sacrifice the career: feed the Cleaner Rebecca’s complete professional connection to the case, so she keeps her skills and published work but loses why she became a journalist and how that career led to Miriam. Treat the scar: use the Cleaner to uncompute the residual angular injury at the laboratory, removing the strongest anchor but exposing every record made by thirty years of containment monitoring. Transfer the archive: guide the Cleaner into a prepared isolated record holding a faithful copy of the Hound correlation, then move the animal into curved containment and allow export, at the risk of concentrating the full Scent inside one fragile body. Release and restore: let the Cleaner reduce Scent to 0, let the Hound delocalize, then rupture the animal before it exports Miriam’s family connections; the timing has to be exact, and the returning records can localize another angular organism even after the original Hound has escaped.
End state. The cleanest success keeps Nora as an independent person, holds enough shared history for the family to recognize one another, and removes every recoverable route back to the laboratory encounter. Miriam survives with a coherent life whose beginning she can no longer explain. Rebecca remembers loving her and cannot remember meeting her. Nora keeps two parents and discovers that every childhood story begins after she was already present. The house finally has square corners. Nobody remembers requesting the renovation.
Additional operations
Hot Storage
A secure data centre starts overheating despite falling computational load. A Cleaner is consuming the links among decades of Hound cases, and the files stay intact while search indexes, foreign keys, and analysts’ memories collapse. The cooling system is delaying Angular Export and preserving the Digestive Archive, so restoring normal temperature saves the facility and permits permanent erasure, while keeping it cold buys time as the Hound follows every reconnecting query.
The Perfect Cure
A clinic uses a captive Cleaner to remove traumatic associations, and patients keep factual memory without fear, shame, or pain. Outcomes look miraculous until former patients lose relationships, moral inhibitions, and learned danger responses built from the treated events. The Cleaner has grown large enough to reach every patient through the clinic’s follow-up database.
Branch Gardener
Researchers deliberately release Cleaners into a bleaching Probability Reef, and lost branches return as the which-history records disappear, letting several stranded humans regain access to the present. The Reef also loses every connection identifying which inhabitants came from nuclear tests, shipwrecks, or modern expeditions. Extraction can preserve people or provenance, with no guarantee that authorities will recognize a survivor whose history has been eaten.
The Last Index
An occult library survives a fire with every book legible and no catalogue. Scholars slowly reconstruct the collection, and a Cleaner follows them from citation to citation, concentrating centuries of suppressed Hound encounters in its Digestive Archive. The librarians can let it finish and lose the only corpus capable of explaining Tindalosian ecology, or kill it and restore enough cross-references to summon several manifestations at once.
Palliative Care
A dying Hound stays trapped in a rounded containment chamber by one terminally ill witness, and a Cleaner waits beside the bed, grooming the witness’s medical bracelet. Feeding will release the Hound and erase the encounter from the witness’s remaining life. Intervention preserves the history and prolongs both creatures’ suffering. The witness understands the choice and asks the Protagonists to leave the door open.
Field classification
TINDALOSIAN CLEANER Type: angular causal scavenger and record symbiont Habitat: archives, hospitals, manifestation sites, data centres, witness households, and other dense record networks Diet: mutual information and causal linkage associated with angular encounters Behaviour: follows correlations, ingests record relationships, exports entropy, and reduces Hound Scent Movement principle: spatial locomotion or Backward Foraging along a surviving causal edge Primary sign: accurate records stay individually legible while indexes, names, provenance, and relationships disappear amid unexplained heat Containment principle: map the Record Graph, isolate valued edges, interrupt digestion, and guide feeding with authentic sacrificial correlations Critical hazard: death ruptures the Digestive Archive and restores every correlation not yet exported
Where the science ends
Landauer’s principle, the thermodynamics of logically irreversible operations, mutual information, reversible computation, uncomputation, and quantum-eraser experiments are established science. Information is physically encoded, correlations can be transformed, and erasure has thermodynamic consequences. None of it provides a method for deleting historical causation, selectively removing the meaning of a marriage, travelling through provenance, healing wounds by erasing their consequences, or exporting macroscopic entropy into angular space. Quantum erasers alter accessible which-path correlations in controlled experiments; they do not erase recorded events from the world. Reversible computation needs access to a process’s physical state and does not run human history backward. The fictional mechanism grants the Cleaner physical access to a causal record as a reversible computation, plus an angular reservoir that can receive the exported correlations. The creature’s heat, need for adjacency, digestion latency, and catastrophic archive rupture follow from taking that invention seriously.
Sources and further reading
- Rolf Landauer, “Irreversibility and Heat Generation in the Computing Process”, IBM Journal of Research and Development 5 (1961).
- Charles H. Bennett, “Logical Reversibility of Computation”, IBM Journal of Research and Development 17 (1973).
- Antoine Bérut et al., “Experimental verification of Landauer’s principle linking information and thermodynamics”, Nature 483 (2012).
- Lídia del Rio et al., “The thermodynamic meaning of negative entropy”, Nature 474 (2011).
- Yoon-Ho Kim et al., “A Delayed Choice Quantum Eraser”, Physical Review Letters 84 (2000).
Final incident note
Ortiz eventually remembered why she had married Rebecca. The memory came back when response personnel cut open the Cleaner. So did the Bellweather case index, three suppressed autopsies, two hours of security footage, and the reason the archive room had been built without corners. Blue vapour appeared before the animal finished dying.
