Just like you , i have some theories too that the author can choose from now:
1 - MC actually dies and becomes an NPC in Eternum (it would be really insane and the most "realistic" thing to happen, it would also be revealed how death interacts with Eternum since the MC would experience it firsthand, but I think it's still too early to this happens and the only person who could notice this and find him would be Calypso, if their "connection" remains active and MC not lose his memories).
2 - Just like Idriel changed dimensions, MC has already had several "living dreams" which is him increasing his affinity with Eternum and perhaps this allows the MC to either teleport to Eternum and heal himself as happened previously in the bar with Calypso, OR, the gift from the "founder" activates, as it saves you from death 1 time "no matter what happens".
3 - MC just doesn't die because of his "power" and it is finally explained why he is "special" (i think it's the worst choice).
4 - Calypso was in her ritual for a loooong time to gain knowledge and perhaps she will gain more power too at the end, as it was revealed that she "feels" the MC energy change/presence, even though it is unlikely, she could create a portal to seek the MC before the police arrive at the scene and save him in Eternum, if Idriel can why can't one of Eternum's "Secret Weapons"?
5 - The woman who is "following" the MC in the shadows, she appeared briefly at the end of the Hunters vs. Demons, for me she is a total stranger, which could be a player, if so the chance of her also following the MC outside of Eternum is high, she would end up being able to save him from death if she was there.
6 - "THE DOPPLEMORPHER!"
This is by far the most bizarre theory, but we've already had several flashbacks explaining various events and actions, even though it's crazy it wouldn't be so unbelievable that the MC or the girls do something with the artifact to change or prevent the MC death...
7 - MC goes to "limbo" and together with Idriel he will "break the chains", I don't know exactly what Idriel's speech means, maybe it's changing the future that is already written or "breaking" the barriers that separate the dimensions of Eternum, this is the most confusing thing but Idriel made it clear that it is better to die than not "get" to die, maybe this is related to the death of the MC but it would also be a strange thing to happen, since this implies that Idriel led the MC to death.
8 - I'm just raving about it and it's totally unlikely to happen, but...
"IF" what Idriel says is completely true, that there were several attempts before and they all failed, "MAYBE" the MC could be a reincarnator, which would explain his power having activated after the near death of Thanatos, because Idriel says "you won't remember anyway" so many times and because "only" the MC can save Eternum. The problem with this is that it would raise the possibility that they wanted to save Eternum before the "founder" found out, as it would take several years for so many attempts to fail.
I only really thought about this shit hypothesis because in the dance scene with Penny on the Vampire route, the MC openly says that "HE DOESN'T KNOW HOW HE DOES EVERYTHING HE DOES, BUT HE EXECUTES EVERYTHING HE TRY PERFECTLY", just like he never learned to dance, but he dances easily guiding Penny in a random very old music AND would this also explain why Luna can't see the MC's future, perhaps because he isn't "human"?...
Regardless of the route, the most curious thing for me is why the frequency that Idriel appeared and influenced the reality around the MC so many times recently, the impression it was giving was that Idriel was manipulating the MC "mind" and the dimension but this ending got everything confusing, Idriel said that she knew everything about the future but this event wasn't planned...
We just couldn't trust her so blind anymore.
0.8 could be the pinnacle of the story and there will definitely be a lot of interaction with Idriel.
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