Authors note: So this is my first Steven Universe story, I just got into the show and I'm absolutely loving it, blew my mind how good it is and it just seems to get better every new episode too. I decided to make an unusual story here, something I won't spoil until you see for yourself. What I will say is that it is a crossover story but it does not have any crossovers with anything else on this site, until now. Hope you guys enjoy and review.
P.S. - This chapter is really just a bunch of backstory about the Gems and their old foe who you'll find out more about as the story continues.
Prologue: An Old War
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Thousands of years ago, before the dawn of humanity, the Gems were once a proud race of celestial and magical beings, born with amazing abilities that give their race amazing powers and abilities, and all share the trait of having a magic crystal embedded somewhere on their bodies, the source of their powers that give them the ability to summon special weapons, along with channeling their strength to power whatever unique abilities each Gem is born with.
The galaxy is vast and expansive, several worlds belonged to the Gems and further increased their influence and power, with nothing in the galaxy able to defeat such a mighty alien race, the Gems prospered and had a golden age that lasted for eons, with seemingly no end to their prosperity.
But great power can easily corrupt those who wield it.
As time went on, the inner politics of the Gems slowly formed a massive rift, several Gems found out horrible secrets of their kind stripping entire resources and exterminating life on entire worlds for the sake of their empire, having no regard for any living thing while moving on to repeat the same process, causing civil disputes that only increased the separation of the Gem race.
Things only got worse when Gems seeking to protect life filled worlds decided to rebel against their kind and defend the same worlds to preserve, only to be met with the same fate of extinction while their government covered up the incidents and regarding them as mere accidents.
Then, out of seemingly nowhere since the Gems were too distracted by their own civil politics… THEY came.
THEY were an alien race just like the Gems, THEY were also an expansive empire with great power, their influence just expanding to Gem controlled worlds who made first contact with the new aliens, seeking to have peaceful relations with a fellow empire and establish a treaty of friendship.
THEY refused. THEY didn't even respond before invading several Gem worlds, managing to wipe out all resistance and strip all resources off of Gem worlds, both organic and inorganic, eerily similar to how the Gems would strip worlds of all resources as well, but in a more brutal and efficient fashion, showing no mercy to those who begged and turned entire planets into bare wastelands in a manner of moments.
A great war began after that, THEY and the Gems fought for years, suffering great casualties in both sides of the war, but THEY pressed onward, no matter how many THEY seemed to lose, THEY still kept going, driven by their power and greed to exterminate the Gems, deeming them inferior beings that deserved nothing but death.
The Gems began to lose the war, underestimating their unexpected foe's power and vast armies THEY had, THEY had more technological innovation than the Gems all those years ago, wielding powerful technology that the Gems either had no idea how to create or refused to create, THEY had much larger numbers than the Gems, armies and armadas that outnumbered the Gems ten to one, and along with the political strife that still continued to separate the Gems, even after THEY were gaining the upper hand.
The Gems were on the verge of true extinction at one point, most of their worlds were either wastelands or still under siege, cut off from all support as the majority of the Gems were trapped on their Home world, preparing their defenses for what could have possibly been their final battle. The Gems were not usually afraid of things, but for the first time in their history, they were truly scared of not just their extinction, but of THEM as well.
The siege of the Gem Home world was long and bloody, it started like any ordinary invasion that THEY would do. THEY would send in scouts and spies, scoping out the planet to know its strength of its defenses and any potential weakness it had. It made the Gems paranoid and worried, as they waited for days, weeks, even months for the siege to begin. But it felt like centuries for the Gems, anticipating a massive force to come crashing down yet it never came, inducing a form of psychological torture of expecting something big to happen but never does.
And when they least expected it, THEY came down with force.
A massive invasion took place on the Gem home world, THEY were throwing everything they had at the Gems, who were already weakened and split apart by several negative factors, giving THEY the chance to wipe the Gems off of the face of the universe. When all seemed lost for the Gems, a miracle happened, a miracle under the name of a special Gem
Rose Quartz
Rose, although being a Gem who opposed her kind from stripping all life from worlds, managed to briefly unite all Gems under her authority for a common goal, survival. The Gems, now united once more, fought back their invaders with everything they had as well, catching their numerous foes by surprise with their renewed faith and hope, pushing back the alien siege to the point of wiping out almost every single invader on the Gem home world, forcing THEY to retreat and dealt a massive blow to the invaders, severely weakening their military strength in the galaxy since a large majority of their forces invaded the Gem home world.
Victory came at a cost however, Rose Quartz had shed several tears after the battle ended, and struck by the loss of several brave Gems who died in battle or were killed in cold blood. Rose managed to push onwards however, leading the surviving Gems on the Home World to take the fight back to them, going to world after world to save other Gems still under siege and increase the Gem's hope and strength, slowly bringing her race back from near extinction and push back their superior foe.
In one last battle against THEY, the Gems defeated whatever was left of the invaders, decimating their moral and power completely after striking a killing blow, eliminating their leader who commanded the entire force, a supreme commander who went by the name of Xeres the Eliminator.
Rose led a final assault on the invader's mothership, bringing along her closest friends Pearl, Garnet, and a few others to infiltrate and destroy the remaining leadership that the invaders had. When Rose and her Gem companions finally confronted the commander, after countless battles against the crew of course, Rose tried to negotiate with Xeres, wanting this war to end peacefully and halt further bloodshed on both sides.
With all forms of negotiation failing to break Xeres, Rose asked the cruel commander with all her heart, why was he still continuing this war, even after all that has happened, after all the death and chaos that had ensued, after all of the loss in both sides, she wanted to know why Xeres still continued it.
Xeres just laughed at Rose's question and gave an answer that the Gems would always remember.
"Because your kind is weak and insignificant. You Gems are nothing more than mere specks of the entire universe, desperately trying to cling onto your old beliefs while constantly contradicting yourselves in hypocrisy and lies. Gems are but pests to our glorious empire, deserving nothing more than death to us, a superior species with every right to exterminate weaklings such as your kind. And I swear to you that although we will lose this war and my life, we will come back and finish what we have started here, no matter how long it takes, we will exterminate your kind and purify this galaxy! We will return!"
Those were the last words of Xeres before he activated a self-destruct sequence on his ship, rather wanting to kill himself than to be taken in alive and face his actions that he felt justified doing. The Gems managed to escape alive before the mothership blew up, and the remaining invaders fled from the Gems, retreating back from wherever THEY came from and were never seen again.
Xeres's words meant a lot to the Gems, for while there was much hate and wrong to them, there was also a bit of truth as well, which further shaped the Gem's views on their way of life, some believing that Xeres had a point while others believed he was a liar. Either way, the Gems still took his words by heart, and those words would help shape the inevitable future to come.
After the defeat of the aliens, the Gems returned to their worlds to help rebuild their once vast empire, but quickly returned to their old ways once more, fighting amongst each other for the preservation or extermination of life in the galaxy, culminating into the events that created the eventual split of the Gems, the Home World Gems who sought out further expansion through force, and the Crystal Gems, guardians of their new found home on Earth and defenders of its inhabitants, humanity.
In these days, the Crystal Gems are but a very few amount, for only Pearl, Garnet, and Amethyst survived the war while the other Crystal Gems had perished, including Rose, while the Home world Gems had left Earth alone, seeking to conquer other worlds and ignore Earth for now, until recent events involving Home world Gems arriving to Earth to discover the Crystal Gems were still alive and well, and were still opposing their rule despite their few numbers.
It didn't matter to the Crystal Gems however, for they would still be dedicated to being the guardians of their home and of humanity, and no matter what threat comes in their way, they would be there to protect their home.
But still, the lingering memories of THEY lingered in Pearl and Garnet's minds, Amethyst was only told stories about THEY since she was not born during that ancient war, but it scared her to think about THEY just from the stories she was told, and Steven Universe who is the newest Crystal Gem and Rose's son, was never told of THEY since he was not old enough to understand such creatures.
Garnet wouldn't dwell too much on such creatures as THEY and Xeres for long, but Pearl was always someone who liked to remember the good things about the past. But good things would also remind Pearl of bad things as well, Xeres and THEY being part of it.
It always worried the Gem too, since every night while no one is looking, Pearl would sneak away from the other Gems to stare up in the stars in deep thought in worry and fright, still remembering the words Xeres said all those years ago.
"We will return!"
Those last three words ringed in her head all the time, because of the way Xeres said them, not with malice and venom, but with brutal sincerity. She knew that he meant every single word from his vengeful vow, and would always think about THEY ever since, and would stare up in those skies in fear of anticipation of their old foe, their name that the Gems only referred to as THEY or THEM, but they knew what their cursed name was, a name that THEY constantly reminded the Gems that Pearl only said in her mind.
"The Hierarchy."
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P.S.S. - If you guys didn't figure it out, which I know you didn't since it's not very popular. I'm using the Hierarchy from a game called Universe at War. It's pretty underground, but I always thought the Hierarchy were a very cool alien race and I thought would be interesting to use in fanfiction crossovers, so I picked Steven Universe since the Gems would be the best chance I could think of at the moment. See you later!
Disclaimer: I do not own Steven Universe and Universe at War (Great game though)