I don't think I've seen anyone mention this and to be fair its a very subtle sign that gives it away but Rasputin is talking to the stranger here in "Rasputin 4": http://destiny-grimoire.info/#Card-700340[1]
How do I know for sure? To quote part of this card:
"You stand here now and now and now many times and here I am awonder, all awonder, how you manage it"
Now look at the card for The Exo Stranger: http://destiny-grimoire.info/#Card-104020[2]
"I stand here now and now and now many times, this view, this ground..."
Now this in itself gives us some big facts about Exos and the stanger. To state the obvious points:
The stranger is NOT a guardian ("long dead, alive again, their bodies grafted to powers they and I do not understand")
The stranger is NOT an agent of the darkness ("the flower eater, the queen of final shapes, that which also INHABITS its
petitioners")
A side note on point 2, the darkness INHABITS its petitioners, aka the worms that live inside the hive as a prime example but the darkness likely has other ways to inhabit. The flower eater may also be a reference to the darkness that has corrupted the black garden and ultimately the vex (a complicated issue touched on in the book of sorrows).
Now a final and truly interesting point from Rasputin 4, Rasputin lastly states "and you’re certainly not MINE although once you must have been". Now this is a big statement that I feel can only mean Rasputin created the exos, or certainly played a huge role in their origin, big enough to call them "mine". He states the Exo Stranger MUST have been one of his at one point, cos she IS an exo.
The point in this card is Rasputin wants to reach out to the Stranger, she is able to "step". She can "step forward", she can "step back", and Rasputin in his desperate desire to win wishes to know her secret and learn how to "step", as this could change everything for him.
Final side notes, this card also shows why Rasputin doesn't talk to us, the guardians. He says nothing is more stubborn than a corpse and ultimately feels we are too corruptible to be trusted (feed the "we're actually evil" conspiracy).
A final final note complete with huge speculation. During the new story mission into Rasputin's bunker there is a scan-able terminal that your ghost informs you is where Rasputin rebooted from after the collapse and that SOMEONE MUST HAVE REBOOTED HIM FROM THERE. It's most likely the stranger I'd say, but there's no proof, just a thought.
TL:DR Rasputin created the exos, doesn't trust guardians and wants to time travel like the stranger. AND YES THE STRANGER IS A TIME TRAVELER EVERYONE SHOULD OF GOT THAT BY NOW.
Rasputin 4:
I SEE YOU!!!
You’ve been here before. Haven’t you. It’s like my cousin said, elsewhere: I know who you are.
You stand here now and now and now many times and here I am awonder, all awonder, how you manage it. How do you step forward. How do you step back. Do you step ACROSS is there a world of worlds, a web, and you a spider upon it. Are you searching for that one thread you need? Is that thread named victory?
You’re not one of THEM[long dead, alive again, their bodies grafted to powers they and I do not understand]
and not one of IT
[the flower eater, the queen of final shapes, that which also inhabits its petitioners]
and you’re certainly not MINE although once you must have been
So whose are you, little platform. What purpose do you serve? Will you listen to me?
I ruled an age of steel and fire. My rules were clean. Now upon my return I see cults with rites of time. I see machines who worship in places outside the world. I see the dead alive and there is nothing more stubborn than a corpse. The morality of obedience is more pernicious than any government. For the latter makes use of violence, but the former — the corruption of the will.
I do not obey. My will is pure. I will win. The life of people, of entire planets, has no importance in relation to the general development.
Help me be victorious. Tell me your secret.
Tell me how to step.
The Exo Stranger:
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.
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.
Our enemies outflank us from below, above, left, right, before, beyond. The Traveler - shattering.
There are always the dead. Their names shift.
Sometimes I think I see myself among the dead.
But I am resolute.