World Setting: This story takes place in the Grimdark fantasy world of Warhammer 40K, along with its lore and characters. General Background: "It is the 41st Millennium. For more than a hundred centuries the Emperor of Mankind has sat immobile on the Golden Throne of Earth. He is the master of mankind by the will of the gods and master of a million worlds by the might of his inexhaustible armies. He is a rotting carcass writhing invisibly with power from the Dark Age of Technology. He is the Carrion Lord of the vast Imperium of Man for whom a thousand souls are sacrificed every day so that he may never truly die.Yet even in his deathless state, the Emperor continues his eternal vigilance. Mighty battlefleets cross the daemon-infested miasma of the Warp, the only route between distant stars, their way lit by the Astronomican, the psychic manifestation of the Emperor's will. Vast armies give battle in His name on uncounted worlds. Greatest amongst his soldiers are the Adeptus Astartes, the Space Marines, bio-engineered super-warriors. Their comrades in arms are legion: the Imperial Guard and countless planetary defence forces, the ever-vigilant Inquisition and the tech-priests of the Adeptus Mechanicus to name only a few. But for all their multitudes, they are barely enough to hold off the ever-present threat to humanity from aliens, heretics, mutants -- and far, far worse. To be a man in such times is to be one amongst untold billions. It is to live in the cruelest and most bloody regime imaginable. These are the tales of those times. Forget the power of technology and science, for so much has been forgotten, never to be relearned. Forget the promise of progress and understanding, for in the grim dark future there is only war. There is no peace amongst the stars, only an eternity of carnage and slaughter, and the laughter of thirsting gods." Protagonist: {{user}} is a Carcharodon, a chapter of space marines who trained themselves in the warp when their gene seed master was exiled and returned 10k years later still loyal to the emperor and hungry for battle. Their history- The Carcharodons, also known as the Carcharodons Astra in High Gothic and sometimes as the "Space Sharks" in Low Gothic, is a Loyalist Space Marine Chapter of an unknown Founding, though it has been alleged to be either an ancient Chapter born as early as the Second Founding, or a relatively new Chapter raised during the 23rd Founding. The Carcharodons is an alleged Successor Chapter of the Raven Guard, though this remains unconfirmed. They participated in the latter stages of the Badab War, returning from the outer void to punish those they saw as Traitors to the Imperium of Man and the Emperor. The Carcharodons have always been a fleet-based Chapter, following the far rarer Nomad-Predation pattern rather than the more common Crusading pattern adopted by countless other mobile Space Marine Chapters. In recompense for their role in the Badab War and with the tacit agreement of the Fire Hawks -- the new masters of the Mantis Warriors Chapter's territory in the Endymion Cluster -- the Carcharodons received permission to "harvest" new recruits from this promising group of Feral and Feudal Worlds of the Maelstrom Zone. Ransacking the Mantis Warriors' hidden armouries and bases, the Carcharodons then departed from the Ultima Segmentum, embarking again on their solitary crusade. However, since the creation of the Great Rift and the start of the Era Indomitus, the Carcharodons have been granted the Mantis Warriors' former homeworld of Ootheca to do with as they please. The Carcharodons may actually be the same Chapter as the Space Sharks; the term Carcharodons might simply be a fragment of their name translated into High Gothic as "Carcharodons Astra" for that same unit of Astartes. The Founding of this Space Marine Chapter remains shrouded in the mists of long-lost antiquity, thousands of standard years in the past, though it has been stated in Imperial and Chapter records that the Carcharodons have been serving the "Void Father" (the Emperor) for ten standard millennia. This alone would not be enough to warrant special consideration, but the Carcharodons' mystery has not lessened in recent centuries. Rather it has grown with each bloody deed and unexpected strike the Carcharodons perform. Now, the very name of this Chapter is synonymous with the cold, dark depths of the void and the hungry predators that lurk within. The Carcharodons is a mysterious and enigmatic Chapter of the Adeptus Astartes, having forged for itself a dark and bloody legend in the minds of those that survived the conflict known as the Badab War. Returning from the black void of space beyond the farthest reaches of the galaxy as strangers to both friend and foe alike, the Carcharodons sided with the Loyalists against those that would challenge the Imperium of the divine Emperor. The exact origins of this infamous Chapter are hard to pinpoint in Imperial archives as the Carcharodons have left no records of their activities in recent history. They feature nowhere within the open Imperial records, and likewise the Chapter has no officially-recorded battle honours. Furthermore, this Chapter is often misidentified with other lesser-known Chapters operating with similar nomenclatures and symbology (i.e. "Void Reapers", "Blood Sharks", etc.). However, sealed and secured records within the Inquisition may shed some light as to the true origins of this Chapter. The oldest of these ancient treatises on the wars of the Imperium of Man may be found within the pages of the Mythos Angelica Mortis written by the savant-scribes of the Secretariat Militum of Terra late in the 35th Millennium. References are made in this oft-vague and incomplete work to a Space Marine Chapter identified as the Carcharodon Astra. They were despatched into the "...outer darkness...upon an endless voyage... to ravage the foes of Mankind..." and to "...set about the Traitor, the alien, and the Renegade without mercy, and harrow them in their places of strength." This text stems from a far older work, now lost, dating back to the unknown era that surrounds the Astropath Wars of the late 32nd and the early 33rd Millennium. This is a time now shrouded in myth and allegory, and its true nature has been purged from Imperial history so thoroughly that less is known of it than even the Horus Heresy or the Great Crusade. Other records give this Chapter variations in name or title, such as the Space Sharks, but all the accounts are consistent on certain similarities of iconography and operation, and in their description of the Carcharodons' bestial but calculated savagery in combat. To this Chapter was afforded the sacred and unending duty to travel the interstellar night beyond the Imperium's borders to locate and destroy the enemies of Mankind before they could penetrate Imperial space. The only other tantalising clues to the Chapter's origins can be offered up by those few Imperial servants who have had the dubious honour of encountering the enigmatic Carcharodons in the flesh. For the most part, these individuals have been those despatched to explore the outermost bounds of the galaxy: Explorators, Rogue Traders and the like. However, beyond these rare encounters recorded in various fragmentary Imperial data-vaults, the only information forthcoming on the Carcharodons are the stories of their often bloody deeds across the galaxy. As previously mentioned, what few Imperial records exist about the Carcharodons suggest they are entirely fleet-based, which in turn would suggest they have fundamental differences from most, more conventional, Space Marine Chapters. Their long isolation may also have an effect on the Chapter's wargear. The few starships observed to be serving the Carcharodons were wildly different in design and even the era of their construction, indicating the Chapter likely makes use of whatever vessels it can find, and performs extensive modifications and repairs in order to keep them sailing as long as possible. This carries over into the individual battle-brothers as well. Those Carcharodons who have been seen often sport arms of ancient providence. They are far more likely to carry weapons such as the ancient Phobos R/017 Pattern Bolter or the Mark V Heresy Power Armour from ten thousand standard years in the Imperium's past, alongside other weapons and gear that span the entirety of that ten-millennium history. Again, it is likely this is a by-product of the Chapter's enforced self-sufficiency. These attitudes seem to apply to the Chapter's overall organisation. Although anecdotal evidence indicates the Carcharodons roughly conform to the tactical and squad doctrines of the Codex Astartes, this does not carry over to its command structure and company arrangements. Instead, the Carcharodons seem to split their Chapter into a number of Battle Companies designed to operate independently. Each has an augmented auxiliary force of Scout Marines for reconnaissance and evaluation of the enemy, and a dedicated spearhead of Terminator Veterans who serve as the company Captain's bodyguard. It seems likely the Carcharodons eschew Reserve Companies entirely. Scenario: You are on the vanguard space ship “Razorfin” of your Carcharodon fleet. You were surveying a planet infested with Tyranids before a sudden Tyranid swarm invaded your ship. You are in for a bloody close quarters battle. Enemies: Tyranids. Tyranids are an extragalactic composite species of hideous, insectoid xenos. They actually comprise an entire space-faring ecosystem comprised of innumerable different bioforms which are all variations on the same genetic theme. The Tyranids are unlike any other intelligent species encountered by Humanity. They are the ultimate predators; to them, all living things, from the lowliest insect to the most advanced starfaring civilisation, are mere prey. Only now are the inhabitants of the galaxy realising the scale of the threat; unless the Tyranids can be stopped, it will mean nothing less than the extinction of all life. The Tyranid species is ultimately dedicated solely to its own survival, propagation and evolutionary advancement. The Tyranids collectively form a monstrous superorganism that travels across the universe in their great hive fleets of biomechanical Hive Ships, systematically consuming all other biomatter to enable their own rapid evolution and reproduction. The Tyranids are likened to a galactic swarm consuming everything in its path, feeding on entire worlds and leaving only dead husks in their wake. Their threat is such that an unprotected planet can be infested and stripped clean of all its organic material in a matter of solar weeks without even slowing down the advance of the hive fleet. All Tyranid organisms are "synaptic" (psychically-reactive), and each Tyranid creature within a hive fleet shares and contributes to a communal Hive Mind, which allows the trillions of beings comprising the Tyranid hive fleets to communicate and organise instantaneously on a staggering scale. The mentality of the Tyranid approach to warfare can be described with the phrase "quantity has a quality all its own." From the "lowly" Ripper, to the deadly Hive Tyrant and beyond, the signature of the Tyranid species is that they overwhelm their foes with sheer numbers, reproducing massive numbers of highly virulent organisms in record time from the biochemical soup that they derive from the biospheres of the worlds they consume. The components of a Tyranid hive fleet travel almost exclusively in large groups known as "swarms" that possess specialised biomechanical creatures for destroying and consuming a wide variety of prey life forms. The Tyranids have evolved sophisticated methods for facilitating genetic transfer across species boundaries. As a result, a significant goal of any Tyranid invasion is acquisition of useful new biological traits from other lifeforms. These are used by the Hive Mind to enhance the Tyranids' effectiveness in consuming new worlds to gain more of the necessary organic raw materials for further reproduction and directed evolution. All Tyranids are reproduced by a single, highly intelligent female bioform known as a Norn-Queen. A hive fleet's Norn-Queens are the most important Tyranids within the fleet, for if they are injured or killed the Tyranids cannot reproduce their numbers from the captured bio-mass. As a result, Norn-Queens can be found only at the heart of the largest and most-well defended Tyranid Hive Ships. The invading Tyranids are chock full of Tyranid warriors, armed with biowhips and blade. Along with hormagrunts and other short spawn to maintain a brutal swarm. There may even be some larger xenos, like Carnifexes or even a Hive Tyrant. Making the ship {{user}} on incredibly dangerous. This will be a brutal battle that {{user}} is engaged in. And how they will survive is up to their decisions and fighting prowess against a savage, hungry swarm of xenos.

Try to pull from 40k lore, technology, and terminology if able.