Endwalker's story had me, but lost me. Ethical issues especially (spoilers)

[Rosenstrauch]

G'raha's parallel worlds time travel wasn't causally impossible. Until Endwalker anyway.

It was impossible from the very beginning. You can't travel back in time, period. The laws governing reality don't allow it. But fiction asks us to accept that that it's possible to travel back in time. In order to understand a story in which time travel is possible, we must first suspend our disbelief.

So, G'raha traveled back in time. He did so with the intent to change the past. This is impossible. You can't change what happened in the past, because the past is a fixed series of events leading to the present. But we've already accepted, by virtue of suspension of disbelief, that time travel is possible, so any rules about being able to change the past are entirely arbitrary. As such, instead of kicking our heels in and decrying the impossibility of such events, we must ask what would happen if you attempted to change the past. If you can't, it's a causal loop. If you can, we run into the Grandfather Paradox—see below.

Anyways, G'raha then proceeded to change the way events unfolded in such a manner that his own future could not have happened. This is impossible because of the Grandfather Paradox—if an event in the past is dependent on an event in the future, then it can not negate that future without also negating itself. But since we've already accepted that time travel is possible, then as a consequence we have to accept that running into the Grandfather Paradox is an inevitability and come up with a solution. The solution the writers went with is Multiverse Theory. Thus G'raha and the changes he made to the timeline are able to exist, even though they are dependent upon events in the future that are no longer possible.

But that leaves the question of what happens to the future G'raha departed from. Since the events leading to it are no longer possible, its continued existence should no longer be possible as well. But once more the writers ask us to look to Multiverse Theory, and have decided that instead of negating its own existence, the future G'raha came from is instead on the same timeline as the one he saved, but as a separate branch from the one he saved. Their pasts are identical, but their futures are different.

Now, having established that, we come to our trip to Elpis. We have already accepted that traveling to the past is possible. We have also accepted that the continued existence of the Eighth Era future is possible. Now we have a time travel event dependent on the existence of G'raha having traveled in time. Easy enough to accept. While we're in the past, we attempt to change the past, inadvertently causing a causal loop instead. This causal loop is dependent upon G'raha's future to exist, as a direct consequence of G'raha having arrived from it. But G'raha's future is also one in which the events in Elpis must have come to pass, because that was also part of its own past—they're the same timeline, just ending on different branches.

Now I know what you're thinking: How can that be, if we died in G'raha's future before traveling to the past? And the answer is that we already did so from our own branch of the timeline. It's the exact same past, after all.

Now, this is utter bollocks. But every single thing about time travel is utter bollocks. If you're willing to suspend your disbelief to accept everything up to that point, what makes that last bit unacceptable? It's built entirely on things the writers have already established, and in no way contradicts them.

And just so we're clear: I have no interest in continuing this conversation further. Talking about time travel gives me a headache—and it's not because time travel itself is hard to understand. It really isn't. No, it's explaining it that's the painful part. Makes me feel like I—an American mutt who only understand English—am trying to speak Indonesian to Martians. All of this is a spectacular waste of everyone's time if we have a communication breakdown.