Afterwards, they could only be grateful that the vision hadn't come during the op. The Saavaasi had finally joined the Third Ecumene, along with the Adonte, but the latter brought with them reports of ships disappearing near the core of the galaxy. Not unexpected; the area surrounding the supermassive black hole hadn't been colonized by the Forerunners, either, but even so the Fleet was sent to investigate.
They did find some wreckage from the ships, but based on what was left, the models of their destruction were inconsistent with being torn apart by tidal forces.
They were more consistent with hostile action.
As John was on his way back to Maethrillian on the Perfect Storm, the vision struck without warning. But this one was different than all the others - it shifted and writhed, actively changing itself before their very eyes.
Truth. The Prophet of Truth. He was still a low-ranker, that much was obvious; his robes were simpler than what the Spartan had seen him wearing as a Hierarch, and he wore no golden crown. He was working at his desk, tapping at a datapad, then the vision flickered, and he was slumped over, unmoving - poisoned. Their work, no doubt. Regret and Mercy both went the way of their fellow Prophet, secretly assassinated by the Fleet in the depths of High Charity.
But then their successors flickered through - no, not successors. Predecessors. The Hierarchs they had deposed in order to take their places as leaders of the Covenant. Still standing, still leaders.
And still the Human-Covenant War played out before their eyes.
I speak to you of my intent, but intentions are eddies and whorls, and they change with the course of a stream
The vision changed again. This time the Fleet revealed themselves to the Covenant after the Prophets' accession, told them the truth that the Prophets had denied them - that while they themselves were not unworthy, humans were the Forerunners' heirs, not the species of the Covenant.
And the coalition fractured, despite their best efforts to hold it together. Some of the factions went over to humanity, became their friends and allies - even the Arbiter, Thel 'Vadam - but there were many who still chose to serve the Prophets, who believed their lies and followed them out into the interstellar void.
When they learned that humans were the Reclaimers, it was inevitable that Truth would order one captured to use on "sacred relics"; that appeared clear as day in their minds' eye.
That, and that the "true" Covenant still found Zero-Four.
But from there, the vision splintered - two possible paths playing out simultaneously. The first path was that they used their captured human to light the Halo, wiping out themselves, a significant portion of the former Covenant, most of humanity, and about a quarter of the Ecumene.
The second path was the release of the Flood. It spread out of control before they could even begin to counter it, still trying to hold humanity and the Covenant steady. Some people escaped, but the Covenant, the UNSC, the Ecumene - all were overwhelmed, same as the Forerunners a hundred thousand years before them.
And again, the Halos were lit to wipe the galaxy clean.
The vision changed again, again matching their changed intent. The Fleet approached the UNSC with a warning about the Covenant, with Forerunner tech for them to reverse engineer and implement as fast as they possibly could. The Spartans - God, the Spartans - the Fleet handled their augmentations and armed and armored them with the best of what they had, so when the Covenant came, they were ready.
But even thought they had been warned, ONI - fucking ONI - couldn't leave well enough alone. A Prowler under their orders - the ship and her crew flickered and changed before their eyes, never constant save in their very presence - slipped through to one of the Halos to study it - and the Flood, to see if it could be useful.
Containment was breached, and again, everything was washed away.
The vision changed, one last time - not of the future but of the past. The Origin universe, John's home.
The Mona Lisa, a frigate converted into a prison ship, now under the control of ONI, arrived at the wreckage of Zero-Four, seeking samples of the Flood for study. The spooks onboard thought they could breed the Flood into their control, thought they could use it as a weapon, against the Covenant and their more human enemies.
They were wrong.
Containment was breached. The personnel onboard and even the prisoners, human and Covenant alike, worked together to try to halt the Flood's spread, but they were picked off in ones and twos. They had sealed the bridge, but the Flood got around that by taking over engineering and building a proto-Gravemind around the Slipspace drive, so it could control the ship directly, without the command consoles.
By the time the Red Horse arrived to check on the ship, there were only a handful of survivors. A detachment of Marines was sent to see what was going on, but they too were picked off in the chaos aboard the frigate. Only a few escaped - including the asshole responsible for the whole situation - but the commander of the Red Horse did his duty and shot the Mona Lisa down, containing the Flood.
There was one last flicker, again of their future - a possibility. A choice.
Alpha Halo. Brief glimpses of the Battle of Installation Zero-Four. The Pillar of Autumn, crashed on the surface, Flood biomass growing over her hull. But the Flood was behaving oddly, not taking down live victims, instead killing their targets and cutting off their headsbefore infecting them. Taking the bodies without the minds, then scrubbing the Threshold system and disappearing before ONI arrived.
With a jolt, they realized that it wasn't the enemy's infection.
It was their own.
Then a voice - voices - speaking from the same veil that had shielded them from the enemy Graveminds during the war: You must let it stand. There is no other option. You're going to have bigger problems.
-------------------------------------------
The vision broke just as suddenly as it had come, and John fell to his hands and knees, gasping and sweating, blood dripping from his ears and nose. [No!] he shouted, [That can't - all this time we've spent planning - all those people - we can't just leave them to die!]
The same grief spread like lightning through the rest of the Fleet; in his memories they had seen the devastation, the cruelty of the almost entirely one-sided Human-Covenant War - Circinius IV, Madrigal, Charybdis IX, Kholo, Alluvion, Draco III - fucking Draco III -
Reach.
Reach burning.
He had been physically born on Eridanus II, but Reach was his real home, where he'd been trained and molded into a soldier, where he'd been born as a Spartan.
(Where he'd met Cortana.)
And now, to be told he had to let her burn-
He crawled to slump against the nearest bulkhead, and pulled his legs up to his chest to bury his face in his knees, and let silent tears drip slowly down.