At this point I think it’s completely certain that the lore is going to take some heavy updates, and precedence indicates that Blizzard will be willing to circumvent logic based on older lore in favor of pushing what they want to do. So, for all our theorizing, it can ultimately come out of left field, and there’s just not enough evidence that even the ‘rule of cool’ would prevail in the final decision. But I digress, thinking like this means there is no point, and how else would I get my 5 minutes of relevance if not through my mild knowledge of Diablo lore.
I’m going to try and make a few pointers to give the Triune a chance. Firstly, they cannnot be the same entity, straight up; more a many generations descended form that’s been influenced by demons and mortals into various directions over time. Too much of the top echelons had been destroyed for the Triune to represent the heart of the order, though Blizzard could easily say ‘oh but that one guy did escape!’. It’s key to note, however, that the lower orders shouldn’t know the truth of what they worship at all. This leaves what’s left of the Triune down to a cultish shadow formed by someone mid to high range that knew just enough to be able to continue the vision, or perhaps be influenced by demons proper into the right steps to survive.
Alternatively it could be a ‘reboot’ of the Triune, which I imagine would be less messy to put together, perhaps at the hands of Mephisto as a contingency plan. It would make some sense for him to be the one given his son was the leader in ages past and he had by far the best opportunity to create a foundation. I don’t find this likely, but it could well be the plans of Mephisto to plant the knowledge of Lilith at least existing in their minds. If Inarius could seal people in the void, Mephisto could surely at least deduce that it is possible his daughter was cast from existence. Perhaps this could tie in with Lilith making faint contact with demons or humans over time even in the abbyss, giving someone the hint that she does actually exist.
Given the limited amount of ways someone in current lore could know she exists, this would probably be the most continuity friendly approach - she made contact with someone, and that someone instigated a plan to bring her. That could pair with the ‘Mephisto made them happen’ deal above, or perhaps someone she contacted became the ‘prophet’, the sole champion of a being supposedly dead for thousands of years.
And finally for another possibility, Inarius could have squawked during his time, though I don’t really see how that would just turn up as something Mephisto or his forces would be looking for. And there we have a point against the prime evil having a hand - they were hardly on the best of terms, either. But, much can change with time.
Rathma would have needed to change much over time for a new cunning streak to show up. Don’t get me wrong, he was clever and deceptive when he needed to be, but he was in direct telepathic contact with Trag’Oul for the vast majority of his later years, and I don’t see the Dragon really standing for it. Both know what happens when Lilith goes on a rampage. It’s not pretty.
Bear in mind that the Ancients of that period were already considered as going ‘out the door’, so in addition to the rest above, it would be a stretch for him to even still be alive. Nephalem aren’t immortal, and he was very ancient by nephalem terms when the Sin War came to its peak.
Inarius who banished her and Mendeln ul-Diomed, first necromancer, who came in direct contact with her when looking for Rathma, who was similarly banished to the void. I need to look up the sequence exactly, because I know Rathma was in the same area, yet the void is a pretty damn big place, and it’s not certain they actually interacted. Easy stretch for Blizzard to make, though, and there’s a good chance both him and Trag’Oul were made aware of the contact at some point. I vaguely recall Mendeln not wanting to bring it up, though; that’s the trick. Next time I comment on the matter I’ll actually look up the scene where this took place.
