The Hive"Existence is the struggle to exist."
Immortality bought with endless murder — a religion of pruning, taught to a prey species by parasites from the Deep.
The Hive were the Krill — three-eyed, chitinous, fragile, and short-lived (their Osmium King is "senile" by age ten). They were born prey, low on Fundament's food chain; one of their oldest verses is literally titled Born As Prey. When the governess Taox betrayed the Osmium Court to a rival nation, three royal sisters fled and swore vengeance: Aurash the navigator, Sathona the cunning, and Xi Ro the warrior.
The buried lore
Diving into Fundament's ocean, the sisters met the Leviathan — a benevolent entity of the Sky (the Light/Gardener side) that begged them to accept their limits and die well. They ignored it. This is the saga's foundational Light-vs-Dark choice, and the Hive chose the knife.
The five Worm Gods at the planet's core offered each sister a larva: immortality and power to reshape their own flesh. The price — obey your nature and feed the worm by killing, forever. Grow stronger and the worm's appetite grows faster. Stop, and it eats you.
Desperate for more power, Auryx confronted Akka, the Worm of Secrets — his own god — and cut him to pieces, taking the secret of "calling upon the Deep." From Akka's remains he wrote the Tablets of Ruin and gained the power to Take. "Now I am Oryx, the Taken King."
Kill a Hive god in normal reality and it simply re-forms in its throne world — a pocket dimension in the Ascendant Plane. That's why every Hive raid fights them inside: Crota's End and King's Fall are throne-world invasions, not field battles.
The Sword Logic
The Hive religion, taught by the worms and sourced from the Darkness: that which can be destroyed must be destroyed; that which cannot be destroyed will surpass infinity. Killing steals a being's existence and proves your own; strength flows up the chain. The whole Hive society is an energy-extraction pyramid — Thralls kill, tithe surplus power up to Knights and Wizards, who tithe to the three god-siblings, who tithe to the worms. This is the mortal face of the Winnower's philosophy: cull the weak, sharpen the universe toward its Final Shape.
The great inversion
Of the three, Savathûn spent aeons scheming to escape the worm-starvation trap — and in The Witch Queen she did, ripping out her worm and being resurrected as the first Hive Lightbearer, wielding the Traveler's own Light. She also tricked Crota into cutting open a path to the Vex Network, and Oryx exiled him for it. The reveal that the Traveler chose to give it to her seeded lasting doubt about the Traveler's intentions. Xivu Arath, meanwhile, needs no body at all — war itself is her avatar; wherever there is conflict tithed in her name, she grows. In Season of the Witch Eris Morn becomes the Hive God of Vengeance and cuts Xivu off from her throne world, leaving the War God mortal.