At the end of Season 19 in Destiny 2, Season of the Seraph, there were many big events happening. It was a culmination of nearly a decade of storytelling. We saw the tragic, final death of Rasputin. Eramis was enacting her plan to destroy the Traveler using the hijacked warsats. The Traveler began to flee. Lightfall is upon us.
What would happen to Guardians if the Traveler left Earth?
There is painful little that we actually know about the Traveler. Since 2014, both in-game and out, NPCs and Guardians alike have been left to speculate what the Traveler is and what its motivations are. What we do know is that when it is under pressure, it will run rather than fight.
The first recorded instance of this is the Whirlwind. This occurred after the Traveler had settled with the Eliksni in their home system. They enjoyed advanced technologies, increased life spans, and many more benefits under the Traveler. However, when the Darkness approached, the Traveler left the Eliksni to fend for themselves. Some chased after it and wound up in the Sol system as the Fallen.
The second time the Traveler attempted to run was during the Collapse of humanity's golden age. Much like it had with the Eliksni, it blessed humanity with the same gifts for reasons unknown. As the Darkness encroached once again, the Traveler attempted to flee but stopped for reasons unknown. For a long time, it was believed that Rasputin had fired upon the Traveler to prevent it from leaving, but the warmind confirmed that this was not the case.
As the Darkness washed over the Sol system, the Traveler created a safe bastion over what would become the Last City on Earth. From this calamity, the Traveler deployed Ghosts to resurrect warriors that would eventually become Guardians. Since then, it has remained on Earth.
For the third time in recorded knowledge, the Darkness has come for the Traveler. Once more, the Traveler has attempted to flee. Eramis, under direct orders from the Witness, planned to enact Rasputin's ABHORANT IMPERATIVE and shoot down the Traveler. Ana Bray, under orders from Rasputin, pulled the plug on the warmind, thus disabling the warsat network.
The Traveler survived but stopped for reasons unknown. Some, like Commander Zavala, believe that it refuses to abandon humanity. However, the Witness claims that the Traveler isn't running because it has nowhere to run to.
We don't know what would happen to the Guardians if the Traveler fled. We do know that its Light can be contained, corrupted, and destroyed. This can then impact Guardians and Ghosts, stripping them of their powers. It could be limited by range, but it's unclear the reach as Guardians have been able to travel the lengths of the Sol system and not lose their powers. At least, not until the Red War when the Traveler was bound.
As for why the Traveler would flee, it all comes down to speculation. We have a crazy theory. What if the Traveler isn't a sentient entity and is instead a construct? What it if was made for the purpose of containing a single entity and was designed to utilize the resources of whatever system it was in to keep its prisoner locked up? What if the Witness is locked away inside the Traveler and the Darkness is desperate to retrieve them?
This would explain why the Darkness pursues the Traveler. It could also explain why the Traveler flees if it is unable to fight back. It would also explain why Guardians came to be. With nowhere to run, why not build a defense force to keep the prisoner guarded, even if unknowingly?
Despite this wild theory, there is one thing we do know that is backed by historical evidence. The Traveler doesn't care about anyone or anything that isn't itself. If able, it will run at the first sign of danger. We don't know what it is, but it's clear that the Light has its own agenda and maybe Guardians aren't on the right side of the fight.
For more Destiny 2 goodies, check out What is the Exotic Mission Rotator in Destiny 2? on Pro Game Guides.