
Originally Posted by
TheMightyMollusk
What makes it a mess is that, thanks to Shadowbringers, we now know that the game works on multiverse theory. Changing the past creates a new branching timeline. So there may have been an "original" version out there. But, we can't time travel freely, so we'll never know.
It seems to me that it only creates a branching timeline if the changes can't be absorbed into the original timeline, though – otherwise the Alexander storyline cannot work.
Our trip to three years ago can be absorbed because everything that happens fits into and does not contradict Mide's memories of what happened the first time she experienced them, even though it recontextualises them with things she didn't notice happening before.
Our later "save ourselves" trip can also be absorbed because what we do the second time fits in with what we did the first time. Alexander just needs to plan that "at an opportune future moment I will send these people back to this moment to break the forcefield" and the loop neatly forms.
If these events created a split, then I don't believe it is possible to return to the present day you came from and still see the consequences of what you "changed" by time-travelling. Either you return to the unaltered version of events (less likely and leaving us without a plot) or you're stuck in this new alternate path of time. Additionally there is another you in this timeline: the version of yourself that was naturally copied into this timeline at the moment of the split while you were the product of the other timeline's copy.
So we cannot have caused a split in the timeline when we time-travelled, or things would be getting very messy.
As for Shadowbringers, I had hoped not to raise that here because the OP is evidently not up to that yet. But I think that is a different and unique circumstance that cannot be absorbed in the same way.
(Shadowbringers spoilers under the cut)
The plot in Shadowbringers is about very deliberately trying to alter the timeline, which causes a split to prevent the paradox of G'raha erasing his own past.
The outcomes I am speaking about hypothetically above – getting locked into an alternate timeline with your alternate self present – are what specifically happens to G'raha. At the moment of the split (somewhere around the present day) he is asleep in the tower and those two split versions of him, the native one and the older time-traveller, will both ultimately end up in our timeline once the time-traveller's actions cause the split.
Though it's worth noting that even in the conclusion to Alexander, the possibility is raised that time could have been altered if we hadn't successfully thwarted the Illuminati's plans to change it. We're just fortunate that for most of the plot span Quickthinx is trying to replicate the "prophesised" events from the book and thus ensuring that they happen to be recorded.