
As seen in Eps. 7, 13, 17, 25, 34, 38, 74, 75, and 77, Satella or the Witch of Envy can either emerge from the dark world Subaru tends to go to after death which I've seen novel readers call the shadow garden or influence the fantasy world directly after he attempts to intentionally reveal Return by Death or even directly break out of her seal located in the Auguria Dunes as seen in Eps. 75 and 77, showing whatever the terms of Satella and the Witch of Envy's seal involves most likely centers around Subaru's safety, which is why she is free to break out of her seal to prevent amnesiac Subaru from being trapped in a bad loop or force specific character development from him, much like when Emilia gave him a huge pick-me-up with what she said about him that gave him the confidence to believe in himself.

I believe this is part of the grand plan started 400 years ago with Echidna since Satella shouldn't know at which points to set Subaru's savepoints or when to interfere since even if Subaru existed 400 years ago, what worked then may not work now especially given Subaru very well failed as the Hero of the story 400 years ago, meaning Satella's knowledge of when to set a savepoint requires future knowledge, and Echidna's the nost likely candidate for having the knowledge given her Authority of Greed: Tome of Wisdom, Roswaal's not-quite-Tome of Wisdom, and potentially the Witch Cult Gospels as well. And that's why I proposrle that Satella has a contract, oath, or some sort of soul link with Echidna in that Satella shares her field of vision with Echidna for some unknown price we viewers aren't privy to.

If Satella did have this sort of arrangement with Echidna, it'd explain why she makes the save points she does, and it'd be 'cause she consults with Echidna beforehand, who we know to have future knowledge and acts with it in mind as shown when she turned Petra's handkerchief into a spectral knife for Subaru to kill himself after he revealed RBD to her. Echidna also looked forward into the future hundreds of years ago given she made Puck with the express intention of defeating Melakuera only for Puck to lose his memories so that Roswaal could draw Emilia into his camp with Puck losing his memories of the Roswaal who co-existed with Echidna four hundred years ago, making him oblivious to Roswaal's Soul Transcription. Certain parts of the fandom say that Echidna doesn't use her Authority, but I call BS as she has clearly used it well in advance hundreds of years ago.

As for how the text in the Gospels may appear due to Echidna, given Roswaal’s not-quite-Tome of Wisdom didn’t include Otto in it, I posit that this is also the case for that text as well, and it was also meant to keep the world on a particular path rather than be a true future-telling text and since the prototypes of the Witch Cult Gospels is Roswaal’s not-quite-Tome of Wisdom, they may be partially made of the same materials, such as Echidna’s fingernails, toenails, hair, body hair, eyelashes, eyebrows, dead skin, or body fluids, and if they are indeed partially constructed by such materials, the Witch Cult Gospels and Roswaal’s not-quite-Tome of Wisdom could be connected to Echidna’s mind through magic, and she’s the one who makes the text in the Gospels appear, meaning Echidna may be stealthily manipulating the Witch Cult through her Authority of Greed: Tome of Wisdom with the Witch Cult being created four hundred years ago so that it could eventually be used to give Subaru and others character development, mostly Subaru.

I wonder what other situations Satella can appear to make things go right if she's permitted to freely interact with the world if Subaru's in major shit like in Season 4/Arc 6, although that may be limited to when Subaru's at the Auguria Dunes or somewhere close to there, including the times when Subaru breaks the Taboo.


[Discussion] Theory: Season 4 shows there's multiple versions of Satella + the Witch of Envy w/ the sealed ones unsealed in Eps. 75 + 77 and those in the dark world in Ep. 74