My version
First things first, Phanes.
The Primordial One *is* the AI from the siblings' ship. The Primordial One crashlanded into the Frost Moon (Moongazer records) and then appropriated technologies and systems from the Dragons there (Lunar Veil, Trilune Authority (which ARE shades of Nibelung's authority), etc).
The Primordial One creates *five* authorities from the Trilune Authority. Logos, Eonothem, Eon, Life, and Death. Logos becomes Phanes. Eonothem becomes Asmoday. Eon becomes Istaroth. Life becomes Naberius. Death becomes Ronova. These are tripartite entities (just like the Moon Goddesses): Body, Soul, Authority. To ensure the five rulers WILL act as they ought to, the Primordial One creates Heimarmene, also known as the Heavenly Principles' rules. Phanes is made into the acting ruler of the Shades, but still constrained by Heimarmene. The mission given to them: transform the world into something the crowned heirs (the twins) can then rule over.
One of the heirs is awakened to help oversee the system, this is the one who will be the abyss sibling. The other is left dormant in the ship, and the ship itself is sent into purposefully long and pre-programmed journey set to return to Teyvat once enough time has passed for the world to have been remade.
The War of the Dragons happens, the sibling does not get involved in it. The false sky is made, and Irminsul's cognitive capabilities are weaponized to control recorded and remembered history.
Humanity is created in Teyvat, but it's not as smooth-sailing as expected. Tsurumi is nailed for understanding the False Sky's existence. Lan Gang is destroyed for developing an Archaeolune-like system that weakens the Shades' powers (the fountain).
The Third Descender arrives onto Teyvat, but they're not a descender *yet*. Seutervoinen/Anacharsis/(not yet the) Third Descender meets Koitar. The Hyperborean Rebellion happens and the Golden City is destroyed by a Nail. Khaenri'ah is founded. The Moons decide to intervene.
Nibelung arrives and the War of Funerary Flame kicks off. Delphi Pytho sinks, two moons are shattered, Apep gets nailed. Sal Vindagnyr gets nailed despite apparently not being involved. Natlantea gets nailed but the damages to the ley lines were too extensive, and so the Night Kingdom is established.
A thousand years later, Monomakh is born from the remains of the Cryo Sovereign. Hyperborea's Primordial Human Project succeeded.
Another thousand years, Seutervoinen/Anacharsis/Third Descender returns in full force and... Makes a deal with Phanes with Heimarmene as a witness/enforcer. The Third's body, the TRUE body (thus why Surtalogi hasn't found her yet), is torn into the seven Gnoses. Koitar is brought back from erasure, but her memories remain locked. The sibling ("the one who came after") gets involved in the creation of the Gnoses. The Archon War starts.
Boreas reaches Amsvartnir and meets Koitar, who recovers her memories and moves north to Snezhnaya. Boreas goes to Mondstadt and clashes with Decarabian. The Archon War goes as everyone knows.
Phanes, at some point, begins the process of their own Tri-Factor Excision to bypass the Third Descender's curse. The three parts are the Body, the Soul, and the Authority. The Body is Paimon. The Soul is the Camera (yes, the fucking camera). The Authority is currently dormant in Celestia.
The sibling arrives to Khaenri'ah with NO MEMORIES of the past. The amnesia might have been Asmoday's doing, potentially at the sibling's own request. Paimon is also summoned to Khaenri'ah, thus stopping the reactivation after the Cataclysm.
The Cataclysm happens, and here's the order of events:
- Asmoday and Ronova move to Khaenri'ah.
- The Sinners refuse to act against them. Istaroth uses Direidyth to keep the sibling out of Khaenri'ah. The sibling, however, went and awakened the Traveler.
- Naberius falls in battle at some point.
- Phanes, right before the curse kicks in, moves the spaceship to the moon as a hail mary to keep the Traveler safe. But it's too late and the ship is now empty.
- Asmoday, lacking Phanes' guidance OR knowledge, cubes the twins as they try to leave Teyvat.
The evidence? Scattered all throughout the game AND the voices inside my head. I might try to gather all the evidence and formalize this at some point, but the mere fact I've written it at all makes me call it a victory. I'm much like Nicole, I'm afraid: A literary giant (if I started writing it down).