"In this world, is it possible to change the past?"
Aether hesitated. What kind of question was that? For him to be asking after such a revelation... it couldn't mean anything good.
"Done." He releases Aether's hand. His eyes are slightly glazed and distant - if Aether hadn't interacted with him as much as he has, he never would have noticed.
"Huh? What the... what happened? Paimon only saw you hold hands for a second..."
"Nothing." He cuts her off quickly. "I was just thanking him for helping me." He turns around. "So long. I suggest you get yourselves out of here quickly." He takes a step forward, towards Irminsul's heart. There's no time to explain to Paimon. Aether rushes forward and grabs his wrist, just as the Balladeer disappears.
"What are you-" "Whatever you plan to do, listen to me. Please, listen to me." Aether turns him around so they are facing each other.
"The past has been changed before in Teyvat, yes. But nothing changed. Events stayed the same, it was just the circumstances that changed. Rather than rewriting history itself, editing Irminsul is just changing the written history, changing what is recorded. Fate is not so easily changed." Aether looks directly into the Balladeer's eyes. Behind the outrage he is desperately projecting, there is despair, and grief. Aether makes a split-second decision and continues.
"There once was the God of the Woods, the God of Wisdom. Her name was Lord Rukkhadevata. She was beloved by her people, and a good friend of King Deshret. At around 500 years ago, a plague began spreading through the land of Sumeru. A plague not of illness, but of forbidden knowledge, information that was the antithesis to life in Teyvat. It spread, corrupting the people and the world both. King Deshret fell to the plague, to the madness that the forbidden knowledge infects you with. Lord Rukkhadevata went into Irminsul to cleanse the world, and was able to remove most of it. But she had also been infected, and she couldn't cleanse herself completely, as that creates a paradox. So she took the purest branch of herself, and created herself anew. And thus, Greater Lord Rukkhadevata and Lesser Lord Kusanali became their titles. And she sat, with the vestiges of herself near Irminsul, waiting for her reincarnation to find and erase her. We did that, after we defeated you. And now, no records of Lord Rukkhadevata exist, yet pieces of her remain in the absence of memory. Rukkhashava mushrooms were named after her, and that's why the Akademiya desired them so much. Their name hasn't changed, but now that piece of their history is gone. All of Rukkhadevata's actions still happened, but they are instead attributed to a Lord Kusanali who lost her memory in the fight against forbidden knowledge. Irminsul fills in the gaps of information that is taken out, that's all."
Aether stops, catches his breath. Usually Paimon could speak for him, but this is something only he (and possibly Lumine) know.
Aether looks back at him. All of the outrage is gone, and he's instead greeted with a numb look he recognizes as dissociative.
"Ah. I see." The Balladeer turns away from him. There is a long moment, in which neither of them speak.
The Balladeer grabs his wrist, a mirror of what Aether had done before. Aether looks up, but his face is shadowed by his hat. In that moment, they are taken outside of Irminsul's heart, back to where Paimon is. She flits over to him, worry deep in her expression.
"Where did you go? Paimon was so worried, not even Nahida could find you two! Don't ever do that again!" Paimon rushes to Aether's chest, and he returns the hug she gives him.
"Traveler, are you alright? Is he alright?" Nahida's voice comes into his head.
"I'm fine, and he's... intact. I don't know what's going on inside his head, but he's definitely not stable. Not that he is at fault for that, given his motivation has been revealed to be a lie." He responds.
"Come on." Aether and Paimon both startle at his voice. "You need my help to get back out." He looks back at them. His voice is flat, far from the snarky, sarcastic tone used in the trip to Irminsul. His face is blank, a constructed mask Aether can't break through. His eyes show nothing. Paimon even notices, and she mirrors Aether's concerned expression.
He turns sharply, and begins walking. Aether and Paimon catch up, and the return is nothing short of somber and awkward. No conversation is had.