Although Geryon typically stood 10 ft (3 m) tall, his serpentine body stretched to 30 feet (9.1 meters) in terms of length and ended in a venom-dripping barb. His humanoid torso was muscular, with massive, bat-like wings protruding from his back, and his large, bestial arms ended in clawed hands similar to paws. Despite his mismatched bodily structure, the Wild Beast had a kind of raw, animalistic presence that made him weirdly alluring and his head boasted a strangely handsome visage.
Before being deposed, Geryon was among the most content of the archdevils, satisfied with conducting his hunts and allowing his subjects to maintain his empire while avoiding the politics that plagued the Nine Hells. He was still an incessant being that persistently pursued his quarry beforehand, but he had become more jealous after being overtaken, applying his determined hunter attitude to regaining his former authority.
While other devils commanded their fiendish forces from a distance, Geryon was vicious and bloodthirsty, preferring to crush enemies with his own two hands. Although useful in the Stygian wastelands, his bestial savagery was also a weakness that negatively impacted his ability to garner souls and forge proper hierarchies. Despite his barbaric nature and his "Lord of the Filth" title, a mocking play on words similar to Baalzebul's "Lord of the Lies" epithet, Geryon was ironically immaculate and preferred a clean environment, leading some to believe he was slightly insane.
Even when diminished in strength, Geryon was a terrifying combatant able to rip mortals apart with only his favored weapon, his claws. He used them not only to rip his enemies to shreds, but to restrain them before injecting them with the vitality-stealing venom present in his stinger, a favorite tactic of his. The former lord of Stygia was immune to the cold and naturally regenerated from most injuries at a frightening rate, but his recovery would be temporarily halted if he was hit with blessed weapons, holy power, or radiant energy. His gaze could strike terror in his enemies and he was delighted by the sight of his enemies cowering before him, whether a natural response or not.
Despite his brutish appearance and typical demeanor, Geryon was still capable of acting tactically, rivaling Zariel in his reputation for martial skill. Weakening foes from afar before closing in for the kill was one of his preferred methods of fighting and he had a wide range of spell-like abilities allowing him to bewitch his foes, take on other forms, manipulate the cold, create a symbol of pain, pronounce an unholy word, teleport, and even grant the wishes of others. He was known to summon gelugons but could also call upon barbazus, hamatulas, osyluths, and pit fiends. He would begrudgingly use weapons if necessary, although he had a tendency to lose his composure and descend into an animalistic frenzy when seriously injured, crushing his foes beneath his fists rather than using any kind of plan.
Geryon's iconic item was his Horn of the Bull, a powerful magical artifact he always kept close that acted as both a dangerous weapon and a symbol of his dominion. Claimed during a quest for Asmodeus from some gargantuan monster, the horn was banded in iron and most creatures that tried to use it had to use both hands. When blown into, the huge horn summoned up to 20 minotaurs to do the bidding of the wielder, although reports on how often it could be used varied between once per day and once per week. The minotaurs summoned served until death but disappeared the next time the horn was used. The exact nature of the summoned monsters was questionable, with some sources claiming that they were stolen from Baphomet and enslaved, while others stated they weren't minotaurs at all but rather a breed of extinct devils that happened to resemble minotaurs. Regardless, Geryon typically used the horn before charging with his summoned monsters at his weakened foes, although it, like its master, suffered a serious reduction in potency after Geryon was deposed.
Geryon was also known to possess two enchanted armaments for situations where weaponry was needed. The first was a sentient battle-axe known as Sever, a weapon forged in the Nine Hells that electrocuted those tainted by good or chaos that tried to wield it. The wicked, sharp blade could communicate either verbally or telepathically and could detect secret traps and passages. The second was a shield named Tonguelash that depicted a giant, devilish face on its surface. It wasn't sentient like Sever, but the mouth area housed a red tongue that would quickly lash out like a whip at the wielder's command, potentially paralyzing the target for a short amount of time, and could let loose a fear-inspiring roar to terrify its wielder's foes once a week.
Geryon's primary residence was Stygia, the untamed fifth layer of Hell and one dominated by frigid oceans and ice floes. During his rule, monuments were made in his honor like the Pillar of Geryon that floated along the River Styx on the iceberg Elgarz. The granite outline, similar to a cave painting, showed Geryon cutting off right hands and replacing them with powerful, fiendish versions, requiring the wielder to commit evil and lawful acts to retain their power.
Originally he ruled the layer from the city of Tantlin, that had been built from one of the largest and most central icebergs in Stygia. After his exile however, Geryon was forced to abandon the seat of his power that beforehand he almost never left, although he had recently managed to reclaim one of his oldest dwellings, the Citadel Coldsteel. Geryon secretly constructed the fortress by hollowing out an iceberg deep within Stygia and it was often compared to a surgeon's scalpel due to its almost clinical sterility and dangerous nature. The majority of the fortress was unpleasantly cold to most devils and lethally so to most mortals staying for extended periods of time, although the bottommost layer was oddly warmer as it went so deep that it was halfway between Stygia and Malbolge.
The mile around Geryon's lair was filled with the sounds of howling, either from creatures or simply the chilling winds, and portals seeming to lead to safety occasionally appeared only to put travelers somewhere else in Stygia. Within his lair itself he had the ability to banish and restrain those before him and cause bursts of arctic energy to shoot out from the ground.
Before being replaced, Geryon occupied himself by hunting those he lured into Tantlin with elaborate plots. He tried to entice the most powerful prey from beyond the Nine Hells with contrived rumors of riches and lore, imprisoning any survivors of the onslaught within his quarries. Although he still enjoyed simple pleasures, like coiling up in his dragon-like treasure hoard, Geryon was brooding and had a new mission; namely putting himself back in power.
Geryon's primary motivation was to regain his lost authority and retake Stygia, so most of his time was spent designing nefarious plots against Levistus. He had carefully crafted a secret army of fiendish mercenaries and renegades and, like Zariel, spawned cambions to act as leaders in his legions. After much scheming, he finally began open warfare against the Frozen Prince, turning the already wild wastes of Stygia into a complete war zone. Outside of those reserved for the Blood War, devils of Stygia were constantly battling for either Geryon or Levistus. This could involve taking part in the never-ending skirmishes that happened throughout the plane or searching for knowledge that could be used to free Levistus or allow Geryon to vanquish him.
For some indiscernible reason, Asmodeus had done nothing to stop the power struggle and indeed Geryon still harvested souls and served the archdevil in hopes of being returned to power. Although technically the ruler of Stygia, Levistus was still trapped in a block of ice, leaving neither one able to directly affect the other. This meant that, practically speaking, two archdevils ruled Stygia, although unlike with Belial and Fierna, the two were fully hostile to one another.
Flanked on all sides by enemies, the lords of the fourth and sixth layers of Hell staunchly despised Geryon. Of the two, Moloch was Geryon's greater nemesis as opposed to Belial, and without Baalzebul's presence, Moloch would have suffered from the Wild Beast's incursions. It was through his unfaithful consort Malagard that Geryon manipulated Moloch and eventually deposed him. Mammon was also a potential sore spot, as the Lord of Greed was thought to had altered his form in an attempt to imitate Geryon and convey loyalty to Asmodeus, although his true opinions on the subject were uncertain. His greatest rival was Levistus; the two had always been fighting over Stygia and had managed to defeat each other numerous times. Despite still serving him, Geryon held a serious grudge towards Asmodeus for his seemingly random betrayal and spent much of his time secretly expressing his rage towards him within Coldsteel.
Geryon also had a retinue of servants, the most trusted and powerful of which was the wolf-headed duke Amon, one of his few lieutenants to survive after he was deposed. Although his consort Cozbinaer, typically shortened to Cozbi, managed to survive for some time using dark magic and machinery to keep her alive, she eventually perished as well. His baliff Gorson also died, but his magistrate Herodias managed to live on. Agares, the duke that rivaled Amon, eventually left in favor of working for Levistus, as did his weakest duke Machalas. Geryon was not discriminatory in his hiring practices and was willing to work with yugoloths and various other races to accomplish his aims. He had once kept a council of creatures from various races, including an erinyes, a medusa, a mind flayer, and a beholder.
Even before he first ruled Stygia, Geryon was summoned by mortals on the Prime Material Plane, an unwise move as he normally took the chance to go on long expeditions looking for rich and powerful opponents. Although no longer a true archdevil, he retained the power to make devilish deals with mortals often through his agents. In exchange for their obedience, Geryon granted raw physical power and enhanced durability to his followers, who were normally found among barbarians and rangers. His ferocity, despite interfering with his ability to harvest souls, was also an important part of his image as a patron of controlled fury and patient vengeance.
Cultists of Geryon were as unerringly self-centered as he was, often times forming bandit gangs or mercenary groups where the weak were plundered and rule was established by proving oneself strongest. His symbol was the frightening head of a bull surrounded by a snake's spiraling body, not only hinting at his serpentine nature but also representing the homage he received from sentient savages throughout the multiverse such as orcs, certain giants such as ogres and trolls, manticores, and minotaurs. He was also known to have servants among standard races, as well as gnolls and the more brutal goblinoids like hobgoblins and bugbears.
Of the few creatures that worshiped Geryon as a deity, lawful minotaurs were the most common. His temples were similarly rare, extremely stark labyrinths of cold, bluish steel. A kind of reverse chapel existed within Coldsteel, used to meditate upon the divine energy he gained from reverence. Although nowhere near close to ascending, reaching godhood was a goal that Geryon still strove towards and believed he would accomplish.
Geryon's origin story in the Codex of Betrayal portrayed him as a champion of He Who Was, the goodly deity Asmodeus himself supposedly worked under. The only ones Geryon cared for more than his master were the other six angels whose team he was a part of that traveled, fought, and worshiped together. One day, the seven were sent to face off against an unrecorded enemy, possibly a primordial at the end of the Dawn War or a creature from the Far Realm, that annihilated four of them and severely crippled the bodies and souls of the surviving three. Unable to properly save all of them, He Who Was supposedly used the essence of the weaker two to save Geryon, hence his later portrayal as a three-headed being with a fragmented personality. 
Geryon was as unimaginably grief-stricken as He who Was himself, but over time his gratitude for being saved turned into bitter hatred when he realized that his deity's patchwork magic had cursed him to feel the thoughts and emotions of his kin, forcing him to relive his anguish forever. It was by appealing to Geryon's desire to silence the voices in his head that Asmodeus eventually swayed him to his side, becoming a trusted general, assassin, and saboteur for the rogue angel. After moving to the Nine Hells, Asmodeus fulfilled his end of the bargain by merging the pieces of Geryon's splintered psyche so that the thoughts of his brethren felt more like hazy memories than vivid experiences. Supposedly the infernal power of the Nine Hells split his form so that he possess three torsos resembling the dead angels and three heads that Geryon spoke out of depending on his mental state; cunning, furious, and manic.
Lord of the Fifth
After his latest displacement of the Serpentine Lord, Levistus had gotten himself sealed within an iceberg for killing Asmodeus' consort Bensozia, leading Geryon to be put back in charge. Some reports claimed Geryon initially disliked the burdens of leadership and preferred his relative freedom, although he eventually came to enjoy the political intrigues of the Nine Hells. He had become much more heinous during his time serving Asmodeus, and wicked deeds that could once be attributed to a twisted sense of loyalty or vengeful fury were done solely out of malevolence. While not particularly notable, his reign was generally stable until the Reckoning of Hell.
The reigning archdevils of the Nine Hells had been putting the final phases of their plans to conquer the plane into action and had chosen their allies in the coming war against each other before they would battle Asmodeus and try to usurp him. Geryon seemingly sided with Mephistopheles, but in truth he was supporting Asmodeus from the shadows all along. He, along with Asmodeus' own agents, had been gathering intel, planting their own servants and converting the commanders of the enemy forces, but took no steps to actually prevent the rebellion from occurring. In fact, Geryon had encouraged his nemesis Moloch to join the battle through the mouth of Malagard. When the lords and their forces were about to finally clash, Geryon blew his horn, signaling every pit fiend commander to turn against their leader and allowing Asmodeus to win the war completely unscathed. With some caveats, every treacherous lord besides Moloch, who had been convinced by Malagard at Geryon's request to remain defiant after defeat, was reinstated, but for some unfathomable reason Asmodeus also deposed Geryon as well, despite his loyalty.
After being stripped of both power and authority what Geryon did afterwards was disputed. It was claimed by some that he simply slinked off into the depths of Stygia to be forgotten for some time. Others reported he became a vestige that wandered the Astral Sea for untold millennia, with rumors that he had simply returned to the astral energy that he was partially made from. He was said to have come across Tytherion and after having brooded in exile for some time, eventually tried to forge his own legacy by offering his emissary services to other planar beings like Tiamat and Zehir, trying to become a greater interplanar influence than other devils. Whatever happened to him after being cast down, Geryon had eventually returned to prominence within Stygia and as he once did, sought to defeat Levistus and return to his former glory.
Rumors and Legends
The fall of Geryon was a target of gossip within the infernal courts of Hell with various speculation and theories on Asmodeus' reasons. One likely idea was that Asmodeus knew that Geryon would end up desperate to reclaim his old position and make him more easily manipulated for later tasks. Asmodeus did indeed play upon Geryon's desires in order to convince him to raid the Temple of Neheod, resulting in the construction of Coldsteel. Another was that the energy stolen from Geryon when he fell was not given to Levistus but granted to Glasya to fuel her ascension into an archdevil. Stories among scholars stated that Asmodeus' particular taste for the souls of those who had lost faith led him to abandon Geryon simply to feast upon his confused and distraught spirit. It was also suggested that it was Asmodeus' warped way of giving Geryon his just punishment for betraying He Who Was, while others thought that freeing the Wild Beast from his infernal duties was a strange form of reward from the Lord of Nessus.
Geryon himself didn't see it as a positive and once came to the conclusion that it would make no sense for Asmodeus to banish him unless the exile was simply a complicated ruse. He theorized that Asmodeus wanted him to do something so unspeakable that simply being associated by proxy would be devastating and that it was left to him to decipher what it was. Although willing to see the task through upon discovering it, he was mortified at the idea of an action not only incompletable by a duke of Hell, but one so fearsome not even the King of the Nine Hells would speak of it. It was thought by sages that even as Geryon waged war against Levistus, the entire situation was part of Asmodeus' grander plan, possibly to root out a better ruler for Stygia or to force both archdukes to grow past their worst flaws.
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