Been a while, hasn't it?
Let's have another crossover then, shall we?
Mantle's Approach
(Inspired by The Mantle of Remnant by KtyouVsWriting and Wolves That Walk Alone by TheManThatWalksTheAbyss115)
Taking place after the prologue of Halo Infinite, the Master Chief, John-117, is mercilessly beaten by Atriox and cast out into space, left drifting for six months as he remains armour-locked in Survival Mode...
Until one day, his armour unfreezes itself, and he awakens in the middle of a crater, in an unknown forest, on a world known as Remnant.
How he got to Remnant is unknown, and it is this mystery that drives much of the narrative forwards as the Master Chief is left on his own, and forced to carve his own path through the world as he tries to find a way off world in order to complete his mission, but soon gets bogged down by the deadly nature of the planet that he now inhabits, and the monsters- The Grimm- That dwell in it.
The same monsters that are wiping out entire settlements and murdering humans (Including the ones with strange animalistic mutations to them) With abandon.
Not on his watch.
Eventually, after months of wandering across the wilds of Remnant, saving villages and singlehandedly destroying entire enclaves and hordes of Grimm on his own (Because if you've ever paid attention to Halo's lore, you know that a Spartan-II can do those things easily), The Master Chief evolves to become a legend across the Grimmlands- An urban myth to its people, of a lone warrior clad in dark-green armour who comes in, saves your life, and leaves all in an instant, without a word and a trace of his existence.
But there was something wrong with that myth.
He was not alone.
He was at first, but not anymore.
Over the days and weeks and eventually months of travelling across the wilds of Remnant, from fighting through bandit clans and packs of Grimm, the Master Chief has slowly been acquiring travelling companions and students alike. An entire class of trainees and young Hunters has formed around him, all of them from all sorts of walks of life, such as Ilia Amitola, May Zedong, Neon Katt, Jaune Arc, Lie Ren, Nora Valkyrie, Sun Wukong, Emerald Sustrai, and even one Ruby Rose, which draws up conflict from her overprotective family as Yang Xiao Long shadows and pursues them constantly, eager to bring her sister back home.
However, that doesn't stop the Master Chief's class of students and trainees, all of them having been brought under the Spartan's wing and brought together, facing trial and tribulation, and eventually evolving into brothers and sisters in arms, becoming a family of found siblings under a unified purpose, of surviving and fighting for a better tomorrow, regardless of the hardships that they have faced.
But with new allies, the Master Chief and his band of students and survivors have also acquired their fair share of enemies. Grimm and bandits aside, the four kingdoms have also taken ire to the Chief's efforts across the Grimmlands, making their Huntsmen look useless and unwanted by comparison. Not only that, but after protecting a village from both the SDC's PMCs and the White Fang as they both fought each other, the Chief and his students run afoul with Adam's faction of the Fang, as well as the SDC at large, with Jacques demanding that the Chief be brought to justice, and drawing Ironwood, Winter, the Ace-Ops, and the Atlesian military by extension.
However, soon, bigger, much deadlier threats arise to confront the Chief, and he and his students arrive in the major settlement known as Argus, where Jaune's sister and her wife and child lived. However, they would soon find that both Saphron and Terra, as well as a majority of the people of Argus, had been indoctrinated into a violent religious cult, with Cordovin's Atlesian division kicked out, and the rest of those who did not believe in the cult's ideology were either killed or driven underground.
The cult's name was the Driven by the One Path...
And their Head Priest was a Sangheili Zealot.
As it turned out, the Master Chief wasn't the only person brought to Remnant by unknown means and reasons. Other groups of aliens and such had been stolen from around the galaxy and placed on Remnant, and this particular group was just one in a hundred, possibly more. Originally just a directionless group of Sangheili that still believed in the Great Journey (Once doing mercenary work for the Keepers of the One Freedom before joining up with Jul 'Mdama's Covenant Remnant right up until it broke apart at Sunaion), Upon waking up on Remnant their leader, a Sangheili Zealot named Rejha 'Vorjadee, used this oppurtunity to begin amassing power for their clan, and over the months that they had been on the planet, had amassed hundreds of human followers to their cause, growing to become the violent cult that they called the Driven by the One Path, and eventually taking over all of Argus and converting a majority of its people to their ideology.
This indoctrination of the people of Argus was assisted by the fact that the Grimm did not take notice of the Sangheili at all. Nor were they affected by any semblances, or any aura stopped them from killing the Huntsmen that stood in their path.
The Sangheili were not impeded by aura or semblance, and as such, on the battlefield, against the Huntsmen, they were practically unstoppable.
This would prove to be the first true challenge that the Master Chief's class of students had, as they were up against a foe that ignored both aura and semblance, and had to rely on their wits and strategic thinking in order to survive. So, as the Master Chief created a distraction outside of Argus, drawing away most of the Driven's forces to confront the Demon, his students were sent in to infiltrate the city and rally those driven underground into a popular uprising.
And rise up they did, ambushing patrols and supply convoys, and destroying refuelling stations and checkpoints. Soon, chaos had consumed the city as the students and uprisers rallied against reprogrammed AK-130s and human cultists armed with swords and rifles, piloting Bullheads and commandeered Paladins, alongside Elite Minors armed with Pulse Carbines, Needlers, and Plasma Rifles, piloting Ghosts, Wraiths, and Banshees.
However, they were slowly being overwhelmed by the Driven cultists, and as soon as Rejha and his fellow Zealots take to the field, an airdrop of additional Driven reinforcements arrived in the city via Phantoms and Spirits, revealing to the students that more aliens had arrived on Remnant than they had previously thought.
For a moment, it looked like all hope was lost for them...
But then the Master Chief arrived.
The Spartan-II cleaved through a swath of human and Sangheili cultists, and challenged Rejha to a one-on-one duel, to which the Sangheili, abiding by his species' code of honour, accepted.
With the Sangheili distracted, the students and uprisers reorganised themselves and began a second offensive against the Driven, destroying their heavy armour and air support via mines and missile launchers, and even commandeering some of their human armour and turning it against them.
Then, luckily for the city, a fresh wave of Atlesian military forces arrived in the city to rescue it from the Driven, and with all of their forces combined, the Master Chief was able to kill Rejha and his fellow Zealots, and the rest of the Driven were beaten back and scattered to the winds, their armour destroyed, and their last members forced into the wild.
However, with the Driven's defeat, the true scope of their plans had been revealed: They were just one of many former Covenant factions that had landed on Remnant, from Jiralhanae hunting packs, to Kig-Yar pirate crews, Sangheili religious terrorists and mercenaries and even lonely parties of Unggoy...
And many of these groups, the Driven included, had formed alliances of their own, joining with human bandit clans such as the Branwen Tribe to form a powerful war machine known as the Joyous March, coming together to survive on this harsh world, and fight against another great foe.
For the Banished had arrived on Remnant as well, and had joined forces with the White Fang to conquer Remnant.
Soon, the Joyous March and the Banished, unimpeded by the Grimm and thereby drawing human, Faunus, and Huntsman alike to their causing, began to march off to war against each other on a world that they had no idea how they arrived on, dragging the kingdoms into the conflict with them.
And the Master Chief and his new students, with enemies at all sides, against a foe that could not be stopped by aura or semblance alike, would find themselves on the frontlines of this new war, fighting to ensure that humanity survived against a foe that they had no defence against.
They would be that line of defence, against these deadly foes.
All the while, in the Grimmlands, Salem plotted with her council on how to use these new arrivals to her advantage, and high above Remnant's atmosphere, Zeta Halo, missing a chunk of its body and heart, hung peacefully in the planet's orbit, an unknown presence looking down on the world with a smile on its face...
(And what was Cinder and her faction doing during all of this? Where were they to capitalise on the chaos?
Well, as it turned out, she had the brilliant idea of bringing an Unggoy called Yayyap into the fold, thinking that he would help her to understand the new arrivals, and also that he would be too cowardly and stupid to turn against her.
However, he also was extremely annoying to her, so she just brought another Unggoy to keep him company and away from her, since the Unggoy's mind was a bit too brilliant at machinery for her to turn away.
Little did she know that the other Unggoy she brought in was a female...
And, well, Unggoy are explosive breeders.)
Yeah, I did just turn Cinder and her faction into the laughing stock of this story, and you're welcome to change it if you want, but this story has a lot of villains in it already, and I like the idea of Cinder being the source of comedic relief for this story, especially when the Grimm can't see the various ex-Covenant species, and she has to deal with the Grunts and all their Grunty goodness by herself.
Cinder: Kill them all. Please. I swear to god.
Grimm: Kill who? There's no one there.
Grunt: On this big spikey rock, next to this mean angry fire lady, we will build the greatest Nipple Academy to ever gas and nipple and academy, where we can eat nipple food and gas for all our days!
Cinder: Kill them all or I will, I swear to god.