Hive Fleet ‘Tempestus Gigantes’ was originally a splinter fleet of the great Kraken, severed from the Hive Mind by a fiercesome Warp Storm. This tempest engulfed an entire fleet of Tyranid Bio-Ships, but only a solitary Hive Craft emerged from the Empyrean, more than two centuries earlier than its original entry.
The awakening Hive Mind sensed the Synapse centres of this foreign ship, and tried to investigate this unknown extension of its system, finding it could not reconnect fully with the bio-ship. The haggard and worn ship had been changed subtly by the Warp, giving the ship and its attendant organisms a degree of autonomy, while still working for the benefit of its primogenitor and trying to pass on gained knowledge to the Hive Mind. This distancing came at a price, as the Hive Mind could sense disruptions in the bio-production bowels of the Norn Queen, leaving the living craft unable to sustain large-scale production.
When the bio-ship re-entered real space, it did so near several uninhabited, but lush, worlds, allowing the “fleet” to gorge itself before being unceremoniously swallowed by the Warp again.
Half a century later, the Hive Mind felt the Fleet it thought lost reappear, isolated and far from other tendrils of its influence. Still unable to take total control of the lone ship, the Hive Mind prompted the production of a huge Hive Tyrant, utilising strands of Trygon and Tyrannofex DNA, to direct the errant swarm using the awesome tactical knowledge of the Swarmlord.
This Tyrant, later codified as ‘Typhon’ by the Ordo Chronos, was given control of the swarm, and its directive from the Hive Mind was to gather as diverse and varied a genetic profile as it could during the fledgling Fleets existence. Perhaps unsurprisingly, the Hive Ship was swallowed up once again by the Empyrean, and thus began the cycle of Hive Fleet ‘Tempestus Gigantes’. Whenever and wherever the Bio-Ship re-appeared, the Tyranids would swarm to the surface, destroy and consume, but the larger organisms were fiercely held in check by Typhon. Due to the Warps influence on their Norn Queens bio-production, it was harder to produce large Tyranids on the ship, so anything larger than a Warrior was restricted from gorging on the valuable bio-mass. These monstrous creatures would become the Fleets defining feature, held dormant on the ever-growing Bio-Ship, rather than being digested and reconstituted.
As the Fleet passed erratically through time and space, they began to gather more and more bio-mass, small confrontations with the Eldar and the Orks giving rise to Zoanthropes and Biovores. Malanthropes were produced regularly, selecting and harvesting unique strands of DNA, and more diversity was fostered in the swarm, all under the direction of Typhon.
This particular Hive Fleet was to be redefined by a mere coincidence, when the Fleet appeared above the stricken Craftworld Malan’tai, drawn through the Warp to the sheer power of the Dooms psychic scream. Finding the bodies of Eldar shrunken, burnt and useless, the Tyrant scoured the world for anything of use, and eventually recovered the mewling, starving form of the Doom of Malan’tai.
Enforcing its will upon the Doom, the Tyrant Typhon used its colossal psychic abilities to direct their random journeys through the Warp, pushing the bio-vessel to sites of great genetic value. While still travelling erratically, in this way, Hive Fleet Tempestus Gigantes has recovered unique Tyranid organisms such as Old One Eye and the Parasite of Mortrex, each time drawing their inherent skills, knowledge and genetic make-up into the growing swarm.
This swarm has exponentially grown since it left the first Warp tunnel, amassing a great and varied genetic knowledge, gathering huge Tyranid creatures to its host vessel, but continues to appear randomly in time to the Imperium. Evidently its reproductive abilites are still damaged, as ‘older’ organisms are constantly adapted to fit growing needs, and the swarm uses every chance it gets to procure large Tyranid organisms from diminishing swarms.
It is not known if the Hive Mind seeks to reintegrate the time-displaced swarm into its hosts, as the Ordo believes the Warp-affected bio-mass would pollute the general Tyranid gene-pool, similar to the Ymgarl Genestealers. The ‘Typhon’ organism is known to communicate with the greater Hive Mind, sending it new genetic information whenever in range, but its autonomy seems to be affecting its malign intelligence in ways that could become even more terrifying.