Hell

Introduction
What even is Hell? Well, first and foremost, a realm like any other. Also called the Abyss or the Pit, Hell has its own share of nicknames. While it's mainly known as a torture chamber for sinners, the unholy realm is so much more: the home of demons, a birthplace of monsters, and the appointed, inescapable prison of Lucifer. Unknown to all, Hell has one more important purpose: to balance the scales against Heaven, preventing either side from taking over the other and thus tipping the scales of all creation towards destruction.
Entering the infernal realm can happen through lava and fire, yet the most comfortable (although less convenient) way is to use hell gates, a type of structure functioning as a pathway between realms. These portals may seem like regular doors on Earth, while Hell's versions can't be mistaken for anything else. Every sin has one for convenience, and naturally generated, temporary portals may appear all over Hell in random, unpredictable locations. These portals usually lead into the mortal realm, yet some are known to throw the unsuspecting traveler into another location within Hell or a completely different realm altogether.
Related
History
Despite common belief, Hell was created at the same exact moment as Heaven and completely by accident. Inhabitable and hostile, the realm seemed like it would not sustain life… Until the first creatures spawned into existence. Small at first, they could battle the cruel elements and grow by eating whatever wildlife spawned around them. Hydrated by blood and fed by living flesh, these seven creatures kept evolving at an alarming speed and soon became too powerful for the young realm to contain. They were spat out into another world filled with more nourishment to consume and a new enemy to battle: seven winged, equally powerful rivals they came to know as "archangels."
Ravenous from their rapid growth and under attack, the creatures clashed against their enemy, fighting for survival as their opponents fought to eradicate the hellions entirely. As time passed, the unnamed creatures turned to less noble tactics, slowly turning the tide of battle in their favor. However, it was too late—by the time they'd gained the upper hand, the realm was all but dead. Seeing their hunting grounds now stripped of all life and nourishment, the hellish monsters retreated back into their home realm, only to be disturbed once more by a presence they'd learned to know well:
The first archangel, Samael.
As the creatures—now grown to colossal proportions—prepared to kill the intruder, Samael offered them a deal; having witnessed the hunger of his former enemies, he'd lead them to feast on a new land filled with unsuspecting prey. In return, he asked to rule the barren realm and its inhabitants, an offer the creatures first refused. Unrelenting, Samael demonstrated his usefulness by providing something Hell had never had before: water. Seeing their old home now able to repopulate and regrow, the monsters agreed to the archangel's terms, granting Samael authority over the recovering realm. As Hell grew under the fallen archangel's rule, the creatures waited for permission to invade their next hunting domain, growing increasingly impatient as time passed. Eventually, Samael—now known as Lucifer—gave the monsters their prize: access to Earth and its dominating species called "humankind."
Named the deadly sins by their new leader, the seven hellions were released to Earth, soon bringing back trophies of their countless hunts. Realizing the incredible value of the sins' findings, Lucifer kept the trophies to himself, tricking the sins into giving a significant portion of their unusable spoils to him instead. Once the monstrous hellions realized they'd been conceived, they tried to overthrow the fallen archangel, who'd now been empowered by the corrupted souls and thus able to defeat the rebelling sins. Scorned but unable to dethrone their leader, the demons had no choice but to keep claiming more souls, fueling the ruler of Hell as well as themselves.
As the realm kept growing and its power increasing, the deadly sins formed a pact: they would find a way to allow Lucifer's return to Earth and, once their leader would be distracted, finally reclaim the throne for themselves. After all, Hell is no place for angels—especially the one that was able to blindside his supposed allies.
The only problem is to figure out which sibling deserves to rule over the other six, when each and everyone only votes for themselves…
Geography
Spiraling in circles into unmeasured depths, the unholy realm is deeper than it is wide. Vertical travel is limited to pre-existing or dug tunnels and openings between layers, while purely horizontal travel takes more time between destinations. Split into tiers referred to as "Circles," a descent into Hell happens slowly and is filled with countless dangers. From plants to wildlife to its inhabitants, every sentient creature attempts to ensure no soul ever leaves the realm.
The Gates
The very first tier of Hell has no name and is simply known as the "the Gates." Serving as an entrance for new souls and returning demons, the Gates see the most amount of traffic. Offering little to no reason for a prolonged stay, Hell's gateway is merely a long, winding road full of sobbing and lamenting souls waiting for their final judgment. Claiming or harming souls still at the Gates is forbidden, as they have not been assigned to their corresponding Circle of Sin and thus have yet to be counted for.
Circle of Damnation
Next comes the Circle of Damnation: the first stop for mortal souls. Serving as the territory of Hell's bookkeepers and their assistants, the Circle of Damnation is dedicated purely to business. Dominated by a gigantic Hall of Decision, the stream of judged souls splits into seven different paths that lead the deceased deeper into the realm. Any hellion wasting the bookkeepers' time will be swiftly punished and removed from the premise, violently, if needed.
Wasteland
The final layer before the Circles of Sin are the wastelands—empty plains and deserts covered in salt and ash, filled with lava and lakes of blood. Plagued by acidic rain and burning hot winds, remaining underground is essential. No vegetation or wildlife survives long in the wastelands' unforgiving climate, making prolonged survival impossible. A handful of shortcuts offer a way through the layer relatively unharmed, at least in one direction; climbing out of Hell is a completely different story.
The Circles of Sin
Circle of Lust
Further down comes the Circle of Lust—the domain and home of the first deadly sin. Destination to those driven by sexual impulses and obsessions, souls ending in the Circle of Lust are eternally chased and assaulted against their will. Demons serving under Lust's command have free reign over the Circle's signature orgies and are encouraged to devise imaginative ways to break their victims apart.
Circle of Sloth
Next down is the Circle of Sloth; as the least violent of the seven sins, the layer might even be called "comfortable" by Hell's standards. With no place to rest between all the rocks, bumps, and other jutting shapes, those afflicted with sloth are forced to wander forever. Of course, it wouldn't be Hell without some additional punishment—like having the victims motivated by flogging their skin and flesh off in the hands of Sloth's underlings.
Circle of Gluttony
The third layer, the Circle of Gluttony, involves souls accused of excessive indulgence. Whatever type of gluttonous greed the deceased mortal has been motivated by, their senses are stripped away by various methods to ensure they never enjoy anything again. Even getting eaten alive won't save the soul from being reborn straight back into torment; it only means the cannibalistic dinners hosted in Gluttony's Circle never run out of food.
Circle of Greed
Fourth from the top is the Circle of Greed, the destination reserved for those who amass wealth beyond their needs. As the deceased never understood the mass of their hoarded possessions, they will be slowly crushed by a physical representation of their greed. On the rare occasion Greed chooses to host an event of any kind, it involves an excess of gifts to the party's host as the main show.
Circle of Envy
Fifth comes the Circle of Envy, where the jealous and desiring end up. Blind to what they already had and covetous of what they didn't, souls in Envy's domain are continuously ripped apart by their uncontrolled desires. Perhaps surprisingly, Envy's underlings are often praised for their torturing skills as they never stop learning and improving themselves, especially compared to other experts of inflicted pain.
Circle of Wrath
In the Circle of Wrath, the violent and resentful are burned with fire and brimstone as hot as their past rage. Known as the Warlord of Hell, Wrath commands most of the realm's armies, making the second oldest sin the most intimidating opponent of the siblings. As the host of Hell's gruesome gladiator battles, souls ending up in Wrath's command are not limited to torture provided only by demons.
Circle of Pride
Finally, within the Circle of Pride, souls accused of vanity or hubris are dissolved into a faceless mass, no longer able to lift themselves above others. Eternally forced to serve others as their masters, the prideful are stripped of their identities and smelted into beautiful masks for demons to wear in Pride's glorious masquerades.
Circle of Desire
The third-to-last tier of Hell, the Circle of Desire, holds various social gathering spots for hellions. Markets, community hangouts, sadistic playgrounds, and other services provided by Hell's residents—no demon gets bored within the Circle of Desire. As the only tier to include more than one vertical level, the Circle of Desire is the largest single layer in the realm.
Circle of Pleasure
The second last tier, called the Circle of Pleasure, contains the most sinful entertainment Hell has to offer: public torture chambers, gladiator rings, depraved whore houses… Down here, nothing is off-limits. While the Circle above still holds onto some sense of limits and rules, only the sinner's imagination stops them in the Circle of Pleasure. Whatever itch a visitor has, they can scratch it in the last public Circle.
Devil's Pit
The final layer, referred to as the "Devil's Pit," differs wildly from the rest of Hell. An unmistakable change in landscape and climate signals any intruder of their mistake of wandering too far; as the temperature drops from scorching heat into freezing cold, volcanic thunderstorms are a common occurrence and the last warning a curious demon gets. Only a few hellions get the privilege to proceed beyond the hell knights' barracks into the icy throne room of Lucifer—not that many would enter willingly.
Landscape and weather
Attempting to navigate Hell is known to mislead any traveler, inexperienced or not, as the landscape is deceptively monotonous and treacherous. Filled with cracks and hidden holes, even one mistake can lead to a painful death. Formed mostly out of different stone types, salt, and tuff, every step burns the traveler's feet. Wings offer no help as the violent gushes of wind can turn into a forceful downdraft, sending flying creatures into walls and stalagmites. Occasional earthquakes, especially further down, are known to cut off stalactites and pieces of rock from the ceiling.
Despite having no sky, Hell's ceiling is filled with smoke and fog, sometimes simultaneously. A thick cloud cover reflects what little light the realm's environment generates, creating an illusion of eternal red twilight. The air is dry, and rain is rare, acidic, and grey with ash, making survival a nightmare. Any stretch of land can become an erupting volcano at a moment's notice, trapping and killing anyone unlucky or stupid enough to ignore the forewarning.
The realm has two minimally differing seasons: the searingly hot summer and the less deadly yet equally unpredictable winter. These seasons do not follow the same pattern that Earth does but rather span over several years, even decades. During the winter, Hell's arid landscape is more prone to sudden downfalls and stronger winds, while in the summer, earthquakes spread around the realm as the realm's volcanic activity increases.
Whereas Heaven's time is slowed down compared to the mortal world, Hell's time flows much faster, in an estimated ratio of 365:1—one day on Earth feels like a year in Hell, and so forth. With the realm currently approaching its summer, temperatures are only going to go up, creating especially violent turbulence and storms in the Circles near the Devil's Pit.
Flora and fauna
While stripped of most wildlife, whatever survives the realm's climate is bound to fight for its nourishment. Gigantic ticks, malformed rats, and skinny imps are only a few examples of the critters considered native to Hell. What may initially seem dead can suddenly come alive and bite back, as the lands favor minimal energy consumption and ambush predators. With drinkable water only available in the bottommost layers, blood is the primary form of hydration for the realm's residents.
Plants fare off even worse: with a climate akin to Death Valley's summer or the Atacama desert, only xerophytes like cacti and halophyte succulents can survive in Hell. With hardly any rainfall, especially non-acidic kind, the realm's flora provides barely any liquid or calories to their consumer. However, their dried seeds can be used as salty snacks in an emergency, and the leaves sucked dry of whatever moisture the plant has managed to absorb into itself.
As the malnourished traveler makes their way deeper, the variety and type of flora increase drastically. All types of plants in the Caryophyllales family ranging from flowering to carnivorous varieties can occur, occasionally grown into colossal portions. The colorful landscape doesn't last long and merely borders the Devil's Pit, yet it provides a beautiful visual of the only types of flowers Hell can host.
Finally, a manifestation of the realm's corruption has taken over most old buildings and roads in the form of unnaturally large roots. Feeding off blood, overtaken houses are better left alone, though there are still desperate hellions willing to risk their lives while sheltering from the weather. As the tumorous growth keeps spreading, demons are left with less and less space fit for living, forcing them to move into small, tightly-packed communities.
Architecture
Hell's architectural styles range all the way from ancient Roman to Victorian with no particular order or logic, as the realm's residents have picked up ideas and influences from mortal architecture during their visits on Earth. Some buildings are fusions of different styles, patched up against Hell's harsh weather and renovated with whatever materials have been available. Stone, bone, obsidian—a surprising amount of style and decoration can be achieved with such limited options.
Despite the various architectural styles, there is something hellish buildings lack: color. With the constant presence of smoke and ash, only different levels of black and grey are achievable. Even glass created in Hell ends up darkened, filtering most of the light shining through it.
Of course, there is some difference between the demon habitats, depending on their resident's rank. Runts are more likely to live near the wastelands in concentrated slums, sharing what little space they have with numerous others. Workers may have moved into more spacious apartments but will still share common spaces with their neighbors. Overlords and higher-ranking demons have houses and mansions surrounded by high walls and guards to keep the uninvited out. The deeper the demon's home Circle, the more luxurious their residence.
With the emphasis on vertical travel, the space between houses is often filled with bridges and ladders rather than roads. Made from different materials and with different techniques, some have fared against the weather better than others, a part of them rebuilt and fixed, while the rest have been left to eventually break down completely. Decorative pieces, like statues, are rare and reserved for those with the space and resources to keep and repair them.
Technology
Hellish technology has reached the industrial revolution but has since been unable to progress further. With the realm's climate severely limiting any intricate contraptions, coal-powered, simple hunks of metal are the only option. Steam-powered engines would overheat instantly and require an excess of already rare water, while successfully operating trains would require rails and underground tunnels to traverse the terrain. Electricity is out of the question, as is the use of combustible petroleum.
What demons have managed to build are factories—or rather, parts of them. Inventions like the spinning wheel, forging, and papermaking have allowed hellions to mass-produce clothes, weapons, and books, mostly for the rich. While more complicated machines like windmills have been built, none have survived the realm's storms. Some contraptions, like the manual winch, are used by torturers to relieve their physical labor, whereas musically talented demons have adopted a wide range of different instruments to earn their keep. Stoves are used to prepare meat, and wheelbarrows transfer more goods at once.
Despite the average hellion's knowledge of basic, old-fashioned technology, adapting to life on Earth requires patience, which demons don't usually have. Electric devices like smartphones and LED screens may seem like magic, cars move at incomprehensible speeds, and some humans even talk into leather straps on their wrists. Mortal life is strange and foreign and requires time to familiarize oneself with before a demon can say they've caught onto the modern times.
Economics
Hell's economy seems simple at first: the value of goods is measured in coins and not affected by market effects like inflation. What's the catch, then? Well, the value of a single coin can vary wildly, depending on whose soul it's embedded with. These soul coins are created in the Hall of Decision as souls are weighted for their sins, transferring the value of their vices into the currency. A soul corrupted by Envy is more valuable than a soul corrupted by Sloth, but a lifelong sinner may outweigh the single sin of someone else despite their sin ranking higher in value. A Coin Master inspects each coin before releasing them into the economy in an open auction, where anything can be traded in exchange for them, excluding other coins.
Due to their supernatural qualities, soul coins appear golden and can be identified by the sinner's name imprinted in them. The soul-reading ability allows any demon to confirm a coin's authenticity to a degree, making forgery challenging but possible. Cramming several souls into a coin to mask their low value may work until a hellion with more prolific senses notices the scam.
Lastly, a portion of freshly minted coins are offered to the Devil and each deadly sin as a sign of goodwill, ensuring Hell's royalty remains satisfied and can afford their expensive habits. Archdemons and overlords are expected to pay additional taxes to the sin whose Circle they inhabit, the total cost varying wildly between siblings. These fees are transferred to workers to cover the overlord's expenses through rent and other costs, who then may require "apprentice fees" to be paid by any runts working under them. It is common for runts to never get their hands on a single coin, paying for their food and upkeep entirely with work.
Clothing and fashion
While demons might enjoy flaunting their wealth and status on Earth with expensive materials and three-piece suits, clothing considered useful in Hell offers much less variability, their most important function being protection against the harsh environment, durability, and light weight. Common material options include leather, bone, and hair, giving hellish clothing an indigenous aesthetic. Cloth created with spinning wheels is often too warm to serve residents outside of the Devil's Pit but may offer functionality when traveling to considerably colder Earth. Shoes are the most important piece of clothing for any demon, allowing them to traverse the burning lands.
As with architecture, color options are limited to grayscale and bloody red or brown—brightly saturated fabric is bound to lose its color in hours. Camouflage is essential, especially within the wastelands, as the wildlife and primal runt hordes are known to follow travelers and attack at a moment of weakness.
Demons can learn to hide their clothes inside their true and shadow forms, allowing them to smoothly change their appearance to fit any purpose and environment. The same can't be said for their horns and wings, which always require appropriate modifications to worn clothes. Therefore, every demon has at least one wardrobe dedicated to each realm, assuming they can afford more than the bare minimum. It's not uncommon for new demons to stumble onto Earth wearing nothing but a loincloth, sparking confusion and ridicule in nearby mortals; sometimes, not even that.