An idea I had when playing Stellaris, what if the universes of Mass Effect and Stellaris collided? How would that go down? So naturally, I wrote this.

Hope you enjoy it.

Earth, the crown jewel of humanity. A beacon of beauty, something all men and women were proud of. It was the first home for humanity before they conquered the stars themselves… and it would be the last.

Grand Admiral Victor Caldwell gazed upon the home world of his people with great trepidation.

From the bridge of his Battleship, he could see the various fleets orbiting Earth, all carrying out their orders of evacuation.

It pained him to give a planet wide evacuation order, but it had to be done. There were protests, but they soon died down. Humanity as a whole fell silent, they knew what was coming and why they had to leave.

Victor stepped away from the display showing Earth and sat in the captain's seat, he cupped his head in his hands. He hated this, he never wanted to be the Grand Admiral of humanity's fleets. But the last Grand Admiral perished in the largest battle the galaxy had ever seen. Grand Admiral John Holloway, a seasoned veteran of war. Bringing together the largest fleet ever seen in human history, consisting of tens of thousands of war ships from across the empire, old and new. John's fleet was bolstered with huge fleets from their allies in the Federation, three different races joined John's fleet and he found himself in charge of the biggest fleet in the known galaxy. Hundreds of thousands of ships followed John's directive.

The monstrous fleet cut a path straight into the heart of enemy territory. The goal was simple, every ship would utilise the Jump Drive technology, a faster than light drive that allowed for instant jumps across space, no matter the distance. The fleet was to jump into the home system for the extra-dimensional invaders, the Unbidden, and destroy the portal that brought the invaders to their galaxy.

And the enemy was waiting for them, sensors and reports recorded at least a million Unbidden ships. and more constantly pouring out of the portal. A fight for the fate of the galaxy, a fight that was lost. John Holloway's capital ship, a Titan class warship, Light of Sol, a monstrous vessel twenty-five kilometers long, was destroyed halfway through the fight. The greatest ship to ever grace humanity's navy, gone. A crippling blow to their military might, and to the fight raging around the portal.

With John's death, Victor assumed the mantle of Grand Admiral. Majority of the navy had been obliterated in the battle for the portal. Logistics showed Victor that the navy had lost over eighty percent of their naval power. Humanity was no longer an empire that spanned the galaxy, they simply didn't have the ships to maintain control of their systems, the Unbidden steamed rolled hundreds of systems, completely unprotected and at their mercy. The empire had fallen apart, even more so when he'd tried to launch offensive operations to retake critical systems containing resources humanity desperately needed.

Those fights were costly, too costly. The navy had just two percent of their original naval might left. Three thousand, two hundred and fifty-six ships were all that remained after. Humanity in its prime had over one hundred and seventy thousand ships, now its military power was a pathetic shadow of its former self.

Though that was better than what others had. Victor knew that the only reason humanity was still standing was because they had two alien ally empires in between them and the Unbidden. Those empires were annihilated first, giving mankind time to breathe and organise whatever naval assets they had left at their disposal. Shipyards went into overdrive, pumping out as many ships as they could to make up for the losses.

But it was a fool's effort, Earth had time to make just three more Battleship class war vessels, powerful behemoths that were ten kilometers long, equipped with the most advanced weaponry in humanity's arsenal. All other shipyards were to commission Corvettes, they were quick, cheap and fast to produce. But Corvettes were small vessels, five hundred meters in length and just didn't have the capacity to carry the deadliest weapons that humanity had. Then came the issue of finding people to man the Corvettes. Conscription was enforced, and thousands were pressed into service from the inner colonies, undergoing rapid training so that the few hundred Corvettes that were pumped out could effectively enter service.

Once the Corvettes were operational, the Unbidden found the inner colonies, there were barely any survivors. Humanity's survival was on the line. Earth was really all they had left. Any other planets were abandoned in favour of retreating to the safest place left in human controlled space. Now Victor had the responsibility of ensuring the survival of the human race, even at the cost of Earth.

"Grand Admiral." The voice of his Lieutenant and communications officer brought him out his brooding. A young woman named Emma, only twenty years old. The officers of the navy were getting younger as Victor and the remaining governing body of the United Nations of Earth were desperate for people to join the navy. The youngest officer currently serving on the bridge of a ship within the UNE navy was just seventeen!

"Go ahead, Emma," The young women nodded.

"Sir, we are receiving a transmission from the research vessel UNE Northwind, priority level one."

He nearly jumped from his seat at that. This could very well be a matter of life and death for humanity.

"Patch them through!" He said.

On the bridge, a middle-aged woman appeared on the screen, she had bags under eyes and her hair was a right mess, it was clear that she got zero sleep. Though she physically looked horrible, her blue eyes were more alive than ever. She bore a smile on her face, something rarely seen in these trying times.

"Dr Starling, please tell me you've got some good news?" he said.

She nodded with great enthusiasm, "Yes, Grand Admiral. I'm pleased to report that my team and I have done it." She said, positively glowing with excitement.

His eyes went as wide as saucers. "Amanda, do you mean..."

She nodded, "We've cracked it, the unknown object, dubbed 'Tuning Fork', is active. After months of study, we finally got it going. It is as we suspected, a gateway to another galaxy!"

Never in all his two hundred and two years of life had he heard such incredible news.

Large, abandoned constructs were rare but they were present throughout the galaxy, remnants of a lost civilisation. Wormholes that allowed for near instantaneous travel across the galaxy. Activating and maintaining these ancient machines took a vast amount of resources but the benefits of near instant travel across space far outweighed the negatives. The military advantages it gave were astronomical.

However, no such object had ever been found that could transport a fleet to another galaxy altogether. That was until the 'Tuning Fork' was found. Initial research efforts suggested that the Tuning Fork could launch ships thousands of light years instantly, however the data pulled was incomplete, though within the data, a plausible theory emerged. The Tuning Fork could possibly launch a fleet across galaxies. Then the Unbidden arrived, research into the Tuning Fork doubled, then tripled. Soon Amanda Starling, the head of Physics research branch throughout human space was working on unraveling the mysteries of the object. Engineering lent as many scientists as they could, while also working on technology to help them against the extra-dimensional threat.

To hear that the science vessels working on it had finally manage to get it active was a relief.

He couldn't help the beaming smile on his face, their prayers were answered, salvation for the human race.

"We also detected an Othari vessel in system when we managed to activate the Tuning Fork, Grand Admiral."

The smile disappeared. The Othari were the race that created Jump Drive and shared the technology throughout the galactic community. It was also the Othari that figured out that their own invention had created a 'crack' in the fabric of space itself with its constant use throughout the galaxy, bringing the Unbidden to their doorstep.

They ripped the Jump Drive out of their ships after learning of what their creation had wrought. They demanded all races do the same, but the damage was done, and the benefits of the Jump Drive couldn't be just be thrown away. Humanity refused to give it up, the Jump Drive was the same drive that the Unbidden had on their ships, it levelled the playing field in that regard.

Getting rid of it would give the Unbidden an advantage, and the Unbidden would still be around regardless if all the races got rid of the drive or not.

It made the fox-like race more hostile towards humanity and the other races that kept the drive.

If they knew about Tuning Fork and what it could do, they'd jump on the opportunity to use it. And unfortunately, they were the race that came out of the battle for the portal better than any other race. They were weak and on the verge of extinction just like humanity and the others, but they would have thousands of more ships at their disposal. They could easily capture and control the Tuning Fork.

He knew how dangerous it would be to leave the Tuning Fork active for too long, and the Othari weren't stupid, the Unbidden would surely follow them through. Whoever used the Tuning Fork first would surely destroy it behind them, to prevent the Unbidden from giving chase. It was what he would do, the dangers of trying to contact and get every race still clinging onto life to come through the Tuning Fork was too great. The Unbidden moved quickly, their ships slaughtered everything in their path.

Humanity needed to mobilise and move out now, they needed to beat the Othari to the gateway. If there was a slim chance that both races arrived at the same time, perhaps they could both escape, if they were willing to play ball. But the gate would have to be destroyed after being used, it was the only way to ensure their survival.

"Alright, the evacuation of Earth shouldn't be any longer than three more da-"

He was cut off by the sound of alarms going off around the bridge.

"ADMIRAL! Emergency message from Admiral Steven Hackett!"

He didn't have time to respond as Hackett was patched through, the man's worn face told Victor all he needed to know.

'No, NO! Not now!'

"Grand Admiral, the early detection systems have picked up an Unbidden fleet, they commenced a jump towards Sol and have arrived at the edge of the system." Hackett said, his voice grave.

Shit! The evacuations were days away from completion. The navy couldn't hold off an entire fleet of Unbidden ships, they would be slaughtered.

He gazed out to look upon the crown jewel of humanity one last time, he couldn't stand the thought of it being desecrated by the Unbidden, but it couldn't be stopped. The enemy would consume all in their path.

His heart clenched, tears formed in his eyes as he prepared to give out the order that would seal the fate of billions.

He patched himself through to all ships within the Sol system, "This is Grand Admiral Victor Caldwell. The enemy has arrived, all ships are to retreat immediately from the system to the given coordinates." He left the order there, he couldn't bring himself to say anymore. His bridge crew had tears of their own, leaving this system was the last thing they wanted to do. Especially when there were billions of people still on the planet.

Amanda cried silently and Hackett had a defeated expression on his face.

"Amanda, prepare the Tuning Fork for our arrival," He ordered, Dr Starling nodded and ended her transmission.

"Hackett," Hackett stood ready for his orders. He was a good admiral, he would've been a much better choice for Grand Admiral than Victor. "You will take your Battleship, the UNE Killimanjaro and lead the fleet towards the Tuning Fork. I pass the title of Grand Admiral onto you."

"What about you, sir?" Hackett said, shocked that he was just promoted to Grand Admiral, leader of humanity itself.

Tens of thousands of objects appeared on the short-range scanners. The Unbidden were closing in. There was no way that humanity would escape in time, the losses would be devastating.

His gaze fell upon the monstrous Citadel space station orbiting Earth, those serving aboard the fortress were going to die, the only option they had left was to give the Unbidden hell. The Citadel wouldn't hold them back for long, they needed support.

Looking to his crew, he saw the faces of every crew member staring back at him with determination. They would gladly die if it meant they could help humanity live. It filled him with pride.

"We'll buy you time, now go!" He ordered, cutting off the connection. He ordered hundreds of ships to join him in slowing the enemy's advance.

The Unbidden were approaching fast. He felt the engines of the UNE Salvation fire into action, the ship quickly moving through space to engage the enemy.

The Citadel's kinetic artillery was already shooting rounds out in the vast void of space, streaking millions of kilometers through space. the Unbidden fleet thankfully didn't possess long range weaponry, that was the only advantage they had.

"All shields to maximum! Get firing solutions for the Gauss Cannons and Gamma Lasers. Give 'em hell!" He ordered.

"Yes, Grand Admiral!" The crew shouted.

Soon the Gauss Cannons were unleashing round after round towards the Unbidden fleet. The Gamma Lasers streaked across space, the orange lasers looking for the kill.

Soon the Unbidden came into range, their almost transparent fleet open fired.

The shields were rapidly going down, the enemy was relentless in their onslaught.

Dozens of other Battleships and hundreds of fighters joined the fray, desperately trying to hold back the invaders long enough for Hackett to escape with the remaining military and civilian fleets.

"Fire the Particle Lance!" Victor roared.

The main weapon, a hellish laser with incredible firepower. The UNE Salvation fired a massive red energy beam into the enemy fleet. The lance stuck multiple Unbidden ships, bringing their shields right down. The following volley of Gamma Lasers and Gauss Cannon rounds dropped the shields entirely and destroyed multiple enemy ships.

The Unbidden's advance didn't slow down. The other Battleships unleashed their own Particle Lance's upon the enemy, dropping the shields of dozens of ships unlucky enough to be clipped by the weapon. The invaders returned the favour in kind, firing their own guns. Thousands of attacks slammed into the dozens of Battleships that remained behind to slow them down.

Victor was thrown from his seat as the ship shook in protest of the enemy fire. The shields were quickly brought down, the armour being shredded like it was cheese.

Alarms blared throughout the bridge and the crew screamed as they were flung around the bridge. Time slowed as Victor took in the impossible odds before him, against an entire fleet, the Battleships were useless. All around him, the Battleships were turned to dust, the Citadel was still unloading thousands of rounds, but it was heavily damaged.

He took note of the scanners just before they went offline. The human fleet was successfully fleeing the system. Some civilian ships and other navy vessels hadn't gotten away but majority had managed to flee in time. Hundreds of ships were still trying to get off the ground on Earth, they wouldn't make it. But at least he'd managed to save as many lives as he could.

He closed his eyes as the enemy fired upon his ship once more. An explosion tore through the bridge and the UNE Salvation was destroyed.

Hackett hung his head in sorrow as he saw dozens of Battleships sacrifice themselves to ensure their escape. The Unbidden swarmed the Citadel and ripped it apart like it was nothing. Their fleet rests over Earth, bombing it into oblivion. Hackett was now acting leader of humanity, Grand Admiral. He'd do everything in his power to ensure the survival of his people, to honour the sacrifices of all those that had died against the Unbidden.

"Grand Admiral," He looked at his navigation officer, "All ships are ready to jump at your command."

"Do it."

The Jump Drives flared into life and the fleet went into FTL, Earth being left behind forever.

The Jump Drive transported the fleet across space instantly, such was the advantage of the Jump Drive. A small contingent of Destroyers and Corvettes guarded the Tuning Fork and science vessels, the fleet being just over one hundred strong. It was a rather small structure, in comparison to some of the other ancient alien artifacts that could be found throughout the galaxy. Though the rotating sphere in the centre was certainly something to be in awe of. The gravitation force it gave off was insane, it shouldn't even be possible.

Hackett was thankful to see it, it was the key to mankind's continual existence.

However, that was short lived when his scanners went off.

"Grand Admiral! An Othari fleet has just entered the system, they've got a lot of ships to. I put the navy at over six thousand strong. Civilian vessels I place at four thousand."

'How could they mobilise that quickly? Though I thought there would be more honestly.'

He remained calm, this could go one of two ways. Both species being here at the same time meant that they could both pass through the gateway. Or a battle would break out for control over the gateway, it would be the end of them all, the Othari had them out gunned, with just over three thousand navy vessels, the Othari was twice as strong as they were. And the Othari held a grudge against them.

"How many Battleships?" Hackett said.

"I count over two hundred, Grand Admiral."

That wasn't good, they had only twenty-six Battleships left, dozens having been wiped out at Earth.

"Establish contact with them."

Within moments, on the bridge display, a humanoid fox appeared, its fur a deep red colour. It wore plated armour, a tradition of their people.

"This is Grand Admiral, Steven Hackett, Captain of United Nations of Earth vessel, Killimanjaro. Identify yourself."

The fox narrowed its eyes, "Steven Hackett? I was under the impression that humanity's navy was led by another," It said, voice evidently female.

"Victor Caldwell... perished in battle above Earth." Hackett said, leaving it at that.

Its gaze softened slightly at the mention of Earth.

"So, Sol is lost, another home world gone…" She mumbled, but Hackett caught it and it fell into place, the Othari were here because their home world had also been overrun, who knows how many were abandoned, left behind to the onslaught of the extra-dimensional invaders.

She straightened and raised her fist to her chest, "Lord of Ships, Tel'Selum, Captain of the Othari Union vessel, Righteous Fury."

The Lord of Ships, the Othari's equivalent of the Grand Admiral.

"Well met, Tel'Selum. I pray we can work together here and avoid any unnecessary conflict." Hackett said.

Tel's eyes narrowed in anger, her ears that stood tall were now lowered aggressively, "Work together?" She snarled.

"We did our part to prevent the threat of further portals being opened up, getting rid of the Jump Drive. We pleaded with you to be rid of that cursed drive and yet your species spat in our face. The Jump Drive will draw the Unbidden to us, and they would obliterate us all!"

He remained calm, understanding the anger that the Othari felt, they held themselves personally responsible for the arrival of the Unbidden, the gravest sin imaginable.

"I understand perfectly, but the Jump Drive gives us advantages that can't be passed up. Not when the Unbidden are already here. We would be at a huge disadvantage being stuck with the Hyper Drive."

She scoffed, "And what about when you pass through the gateway? Your Jump Drives would summon the Unbidden to the new galaxy."

He sighed, that was something that his predecessor thought about. Humanity would be limited in their growth and development in the new galaxy without the Jump Drive. But Tel was correct, humanity needed to return to the inferior Hyper Drive once they passed through the gateway. The danger of the Jump Drive was too great.

"We will remove the drive from our ships once we pass through. You have humanity's word."

Tel regarded him for a few moments, then grunted in approval, "Good... I suppose we can work together then. But don't believe for one second that our species are friends."

"I'll be honest here, Hackett," Tel sighed, her hostile attitude disappearing slightly, "If you weren't here, we were going to destroy the gateway behind us. The risk of the Unbidden arriving was too great. Conflict would be pointless and stupid, we would only weaken ourselves. I pray humanity has sense to see that we can both pass through the gateway?"

Inwardly, Hackett was relieved. The Othari were desperate for survival just like they were, and they were willing to play nice.

"Glad to hear it, now I think we've wasted enough time talking. Let's pass through the construct."

Tel nodded.

"Excellent idea, Grand Admiral," The voice of Dr Starling interrupted, surprising both Tel and Hackett, "The Tuning Fork is made of an incredibly tough material, nothing we can't destroy of course, I recommend a few timed warheads, should easily do the trick."

"Who is speaking?" Tel demanded.

Hackett raised his hands in a calming manner, "It is Dr Starling, head of our Physics research division. Though I am curious as to how she managed to join our call."

Dr Starling appeared on the screen beside Tel, smiling mischievously, "Your communications officer was so kind as to add me into this little chat, now onto business. Sensors show Unbidden fleets about to jump into this system, they're following you, Grand Admiral."

Hackett went white as a sheet. He quickly gave the fleet the order to approach the Tuning Fork for transportation.

Tel did the same, thousands of ships rushing towards the large alien construct, stopping just before the guard detail.

"Dr Starling, how does this device work?" Hackett said.

"Simple, move your ships next to it, the device will launch your ship to another galaxy in an instant. A Corvette went through and came back through another Tuning Fork device."

Hackett nodded and gave the order for all ships to use the device, as did Tel. Thousands of ships pressed forward, the Tuning Fork's spherical centre began to pick up speed before the glowing core shot tendrils of light that enveloped every ship that got close enough before they are simply vanished into the void of space.

The science vessels went next and then Tel's ship went through the gateway. Hackett was the last ship left.

"Prime the warheads to drop just before we enter the alien construct."

"Warhead primed for de-" Alarms blared.

A fleet of transparent ships appeared, relentless in their quest to wipe the galaxy of all life. And they appeared on top of the construct and Hackett. Their weapons fired upon the Killimanjaro. Its shields melting away like they weren't present.

"GET US OUT OF HERE, DETONATE THE WARHEAD NOW!" Hackett roared.

The Killimanjaro punched it for the gateway, its shielding gone and the armour disintegrating rapidly. Dropping ten warheads, the Tuning Fork connected with Hackett's heavily damaged vessel and launched it through space.

The Unbidden ships rushed towards the object, the construct connected with them, about to shoot them through to another galaxy when the warheads exploded.

The relay destablised before it could launch Unbidden ships, the warheads and the supernova like energy blast from the destroyed relay decimated the entire Unbidden fleet. The explosion went on to obliterate the entire system.

The Killimanjaro found that space around changed in the blink of an eye, and they appeared next to the Othari and Human fleets. Hackett groaned in pain, his ship was nearly wiped out within seconds of the Unbidden appearing, unable to handle that much firepower. It threw the crew around.

"Status report!"

"Grand Admiral, we've sustained heavy damage, armour is practically gone. Structural integrity is holding at just thirty five percent, fires are reported on all decks, we've lost majority of our systems."

"Vent empty sections of the ship to kill any fires, tell the crew to prepare for atmospheric venting." Hackett ordered.

Within in minutes, the fires had spread more and threatened the ship itself as crew scrambled to prepare for venting procedures.

Soon the ship was venting air on each deck, killing the flames, though not without a few unfortunate casualties. The ship was no longer in danger, but it was dead in the water.

Hackett saw incoming messages from the Tel and Dr Starling.

"..kett what happ… ddin?" was the message from Tel, and Dr Starling's wasn't much better.

It was clear they were both wanted answers though.

"Sir, communications have suffered considerable damage, receiving transmissions is out of the question, though we should still be able to send messages." Said his communications officer.

"Good enough, inform the Othari and the rest of the fleet what occurred." Hackett said.

Despite the state the Killimanjaro was in, Hackett couldn't help the sigh of relief. Gazing back at the transportation device, he was overwhelmed by the fact that his species was safe. The Unbidden threat was no more.

Humanity had survived galactic extinction and could now rebuild, though they would never forget the horrors the Unbidden inflicted upon them.

Although Earth and her colonies were gone, Humanity would endure.

What do you think?

The Council races will come into the fold soon enough.