Fate/Grand Order: Kar En Tuk

Prologue

Five years after the events of Doom Eternal...

Earth's Orbit, Fortress of Doom, 2100 hours:

After spending quite some time cleaning up the last remnants of the infernal legion on Earth, The Doom Marine finally eliminated all traces of demonic activity on Earth. All the gore nests have been eliminated, with the demons killed or driven back to their hellish dimension, hopefully to never return again. Raised to a demigod status by the survivors, the Slayer was so much celebrated by them, they even started making religions and cults about him, talking about his deeds just like the myths of heroes from ancient times (Even monuments were been erected in places where he supposed traveled through, in his honor). The mark of the Slayer was engraved in every new human settlement, said to ward off any kind of malevolent creature.

The new human government (formed from the remnants of the ARC), tried many times to contact the Fortress, only to be met with silence. With the invasion over, they wanted to turn the Slayer in their personal "problem solver" and "mascot". Their attempts were only met by either no answer at all or Dr. Hayden saying he wasn't available. For him, his job was over (for now) and he had no interest in their affairs or anything like it. He had only one objective: the complete destruction of the Dark Realm and anything related to it.

In the next day, after some relaxing time at the Ripatorium, the Doom Marine sat down for a bit, picking up a book after his late night workout. He was starting to get a bit more relaxed, this "break" really a blessing in disguise. Because he knew there were still problems coming in the horizon: the demonic tree prophecy of the dark priest, and the "breaking" of the holy seal of Urdak and the mysterious voice in the sky after the defeat of the Khan Maykr. These will probably be the greatest challenges he's ever faced during all his time fighting Hell. But he'll be more than ready to face them all, so they better bring everything they have.

But, to face these looming threats on the horizon, a good soldier must always have his equipment in excellent condition. He almost forgot he had to clean up his armor after his little "fun time" (since he made quite the mess and how of a pain is to clean up the floor of the base and the Praetor Suit too) and some mandatory weapon maintenance. So, enough reading for the day and let's get back to work, he thought. Putting the book back on the shelf, he went on his merry way to the armory. Still, he couldn't shake the feeling that something was about to happen (and the eerie Dr. Hayden's torso looking into the void of space didn't help it too)...

3 days later:

While the Marine was tinkering with his Praetor Suit, a familiar voice sounded in the comm system:

SH: - Marine, we have a problem on Earth.

Said old man Hayden, in an hush tone (as always).

"Those guys never learn huh, I know exactly what's this even before he says a word about it.", he thought.

SH: - The authorities contacted the base half an hour ago, apparently some sort of anomaly was detected in Antarctica. After analyzing it, I determined it to be some sort of time-space fissure there. It could be "them" again or something even worse, since they didn't detected any kind of Argent Energy and or demonic presence. Get everything you need, we need to go investigate now.

This is getting interesting. A fissure like this opening in the middle of nowhere, and no mention of demons swarming through it and setting up their base there. They usually do that and places with humans, to kill them and use their bodies to build Gore Nests. Something was really fishy about this, it was almost like a lure, to attract him there. Still, he needed to do his job (And also, he would never miss an opportunity to crack some demon skulls). Picking up everything he needed to go there (smiling when he got the BFG-9000 and the Crucible), he headed to the portal that was opening in the command room. Giving a last look at the base, he walked right into the teleporter.

Antarctica, 1800 hrs:

In the vast whiteness of one Earth's most inhospitable places, the South Pole made the Doom Slayer have flashbacks of his time in the U.A.C Cultist Base, back in the North Pole. Destroying that base, it's inhuman work and finally exterminating the last of the Agaddon Hunters once and for all, that was priceless. That and seeing the head of the treacherous Deag Ranak rolling in the icy landscape just after seeing the coward begging for his miserable life, that was quite the experience...

After hours and hours of walking through the frozen wasteland (the Marine didn't wanted to rush to it, since it appeared to be nothing more than a harmless anomaly for now), Hayden's voice echoed a little in his helmet:

SH: - The fissure should be very close by now, just after that mountain range. Stay sharp.

After a little bit of mountain climbing, he finally reached the top of range, reaching another white plain. He finally could see his objective in the distance, not much far away from where he was. Approaching it quickly, the fissure was almost like a broken glass window after a kid broke it with a baseball. And what was on the other was very much visible: A city. Not a city from this Earth, since it looked ancient compared to cities in this age, but it still was a earthling city. Completely destroyed and covered in flames. But no signs of humans, demons, not a single life form. Only debris and flames. His observations were interrupted when Hayden came through the speakers, speaking in a rushed tone:

SH: - Marine, the fissure is fluctuating. Something is about to happen, back away from it now!

Indeed the fissure was becoming a vortex, a vortex so strong that even him couldn't hold on for long. Damn, it felt almost like the gravitational pull from Jupiter. Finally, after some struggling between the two, the ground broke and the Doom Marine was sucked into the fissure, the world turning into total darkness for him. It closed with a bright flash and a presence somewhere else was quite pleased with the results.

'So it finally begins, the battle between the Kings of Men...'

TO BE CONTINUED...