So, what does the Future War Cult have to do with all this?
Records of the FWC date back to the late Golden Age and they have access to some very interesting tech from that era. Specifically, a machine that allows someone's conciousness to view different timelines.
Take a read through Ghost Fragment: Future War Cult.
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Subject twenty-two. Admitted to the Inner Circle at 24:00. A promising postulant - I regret to say he performed poorly. He was administered the standard medication but refused to enter the Device.
Aren't people unpredictable? I suppose there'd be no point if they weren't, would there?
He knows to keep silent.
END RECORD
As we'll see below, the 'Device' is the alternate timeline viewing machine.
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Subject twenty-three entered the Device at 11:00. A clever girl from the Core District; an artist, before she joined the War Cult.
At 11:03 she reported a sensation of floating. At 11:06, a sensation of lights within the darkness of the Device. Between 11:06 and 11:32 she reported these lights variously as white, golden, and blood-red. At 11:32 she reported a sensation of someone taking her hand; a stranger, but also herself. Twelve subjects have reported similar experiences. At 11:33 she reported the sensation we have called "The Opening Of The Veil." The Device recorded temporal displacement of her consciousness to the order of six degrees. At seven she began screaming. Brainscans near-death. Removed from the Device at 11:34.
Here we see that the subject's conciousness 'unstuck' in time, however it comes with a great risk and she had to be removed.
She believes without question that the Device granted her a vision of the future, and that it was one of utter Darkness. She thanked me for this enlightenment. She says it will make her stronger.
Again, her brief temporal displacement allowed her to see a future consumed by Darkness.
Little Ghost, there in the corner of the Sanctum - I see you blinking. Are you listening? Are y -
END RECORD
Notice how there's no indication that the narrator switched from reporting to asking a Ghost a question? We can assume that the narrator is actually speaking to an audio/video recording device, which picks up her speaking to other people. I'll get back to this later.
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the Device at 12:22 and immediately the Device reported displacement of his consciousness. Visions of war and the City in flames. Subject twenty-nine worked the supply channels on the Slip before he joined the War Cult. By 12:27 he was babbling and by
END RECORD
Again, another subject, another vision of the future and another grave consequence of using the Device.
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We have applied certain refinements to the Device. Novarro found records of a prototype of the Device at a Golden Age laboratory in Tibet, and Hari's team retrieved what was left of it. We are the first to see it operational in who knows how long.
Too many subjects come back damaged. Mad. We are grasping at straws. What do you think, little Ghost?
END RECORD
This further suggests that the FWC has access to information about Golden Age secrets and know where to look for its tech. They also have the knowledge to make Golden Age tech functional again. Yet, they still can't solve this problem of Humans being too weak for the device...
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Forty-seven human subjects; eleven report timelines in which the Darkness has already prevailed, thirteen report timelines in which the City has fallen. Twenty-three babbled madness. Hopeless. Trapped.
This is where the alternate timelines come in. It's not just a vision of the future, but a vision of lots of futures.
No wonder the Device was abandoned. The human mind is too weak for it. Too weak to look into the Future, or to understand what it sees.
The Human mind is too weak...
What the situation calls for, little Ghost, is a better sort of witness.
We found you in pieces in Siberia, and repaired you as well as we could.
Remember how I said there's no indication when the narrator switches between reporting and talking to the Ghost? Well this happens here again, with a mystery third subject.
Remember, the FWC are well versed in Golden Age tech. There's no way she could be talking about the Ghost, as they're the creation of the Traveler.
I believe they found an Exo in Sibera and repaired her as best as they could.
An Exo not forged in Light
I believe this is who the narrator is now talking to. Think about it, they need a Human to enter the Device, but Human minds are too weak. What's has a Human like mind but is more resilient? An Exo.
What do you say? Are you well enough to travel?
END RECORD
Now assuming the above is correct. The Future War Cult find the Exo Stranger, broken in Siberia and repair her with good old fashioned Golden Age know how, so that she can enter the Device.
What does she see?
Maybe something like this.
I stand here now and now and now many times, this view, this ground...
This is where I always choose to stand. I put my feet where I put my feet before and where I will again and I look at the sky.
This is a recurring vision. Perhaps a timeline that will happen if nothing changes (remember 'thirteen report timelines in which the City has fallen').
Great things moving, rendered small with distance, lesser things not moving, watching me.
I always stand here, resolute. Then fall back to that point, there, where everything shatters...
(The sky isn't special here, certainly no better than any other sky, but it's the view I know best.)
The silent avalanche begins. Rock and dust. Falling chaos. Machines, as a rule, hate chaos.
This is a vision of the Vex invading.
Our enemies outflank us from below, above, left, right, before, beyond. The Traveler - shattering.
An overwhelming Vex force that completely obliterates the Traveler and, presumably the City. 'Visions of war and the City in flames.'
There are always the dead. Their names shift.
Sometimes I think I see myself among the dead.
But I am resolute.
The overall vision is the same, the Vex obliterating the Traveler, but small details change, such as different people dying (which may be due to small changes in the timeline leading up to the big event.
Alright, so now what?
This is speculation on my part, with the above evidence. But my theory is that the Exo Stranger, having access to the FWC's Device, is able to see multiple timelines with most of them ending in the Traveler being destroyed by the Vex.
Until we show up. Remember how it was convenient to find a fully working rifle from the Golden Age just waiting for us?
I believe that the Exo Stranger saw a timeline in which we were able to save the Traveler by defeating the Darkness in the Black Garden. The Stanger anticipated our revival and guided our journey to fulfil that timeline. Giving us enough help to survive, but judging our own abilities every step of the way to be absolutely sure that we're the right hero.
This is why we see her watching our ship take off from the Cosmodrome, this is why we see her watching us on the Moon. After this she contacts us again, from Venus, while we're still on the Moon yet she knows 'what you're about to do' and if we live, to come find her.
Leads us to Venus, to discover the Vex and pretty much tells us to go to the Black Garden to destroy its heart. If it wasn't for her intervention, no one would know about the Vex and they would invade, resulting in the Stranger's vision above.