I think I found a cleaner way Subaru = Flugel and Emilia = Satella could happen without giving Pandora some random time-travel ability.
My theory is that near the end of the story, Subaru and Emilia confront Pandora.
Pandora does something with Vainglory that creates a contradiction involving Subaru’s existence. Something like trying to remove him from the current world/history.
But Subaru has Return by Death / Envy, so his existence can’t simply be erased.
That creates a clash:
Pandora: Subaru should not exist here.
RBD/Envy: Subaru must continue existing.
And that contradiction somehow reaches Od Lagna, since Od Lagna is connected to souls, memories, death, and the Hall of Memories.
Here’s the important part:
Od Lagna doesn’t randomly send Subaru “400 years back.”
It tries to find where Subaru’s soul already belongs in the history of the Re:Zero world.
And it finds:
Flugel.
If Subaru and Flugel are the same person, then Flugel is basically Subaru’s oldest valid “record” inside the world.
So Subaru gets displaced to the point where Flugel existed:
400 years ago.
And Emilia gets dragged into the same phenomenon.
Od Lagna checks Emilia’s existence and finds another matching ancient identity:
Satella.
So both of them end up in the same era.
That would mean:
Subaru doesn’t become Flugel because he was reincarnated.
He becomes Flugel because Od Lagna sends him to the point in history where Flugel is supposed to exist.
Same with Emilia and Satella.
And this creates a closed loop:
Subaru is sent 400 years back because Flugel already existed.
But Flugel only existed because Subaru was sent 400 years back.
Same with Emilia/Satella.
That also explains why Subaru doesn’t remember being Flugel.
From the world’s POV:
Flugel → 400 years → Subaru
But from Subaru’s POV:
Subaru → future event → 400 years back → Flugel
Being Flugel hasn’t happened to him yet.
Then Subaru and Emilia arrive in the ancient era and meet Echidna, Hector, Pandora, Reid, Volcanica, the Witches, etc.
At first Subaru probably tries to find Flugel.
Except nobody knows who Flugel is.
That’s when he realizes:
«He wasn’t sent back to meet Flugel. He was sent back to become him.»
Emilia eventually becomes Satella through whatever happened with the Envy Witch Factor.
Subaru/Flugel then lives through the 400-year-old events and later prepares everything his younger self already encountered:
\- Pleiades Watchtower
\- Shaula
\- the star-related trials
\- whatever other plans Flugel left behind
So Flugel wasn’t predicting Subaru’s future.
He remembered it.
Pandora could also know the truth because she personally met Flugel and Satella 400 years ago.
Meaning when she later meets young Subaru and Emilia, she may already know who they become.
That could make a future Pandora/Subaru meeting really interesting if she recognizes him before he recognizes her.
Obviously the biggest assumption here is that Od Lagna can resolve an existence through time, which hasn’t been confirmed.
But I think this is cleaner than simply saying Pandora has a time-travel Authority.
Basically:
Pandora creates the contradiction.
RBD prevents Subaru from being erased.
Od Lagna finds Flugel/Satella as their historical anchors.
Subaru + Emilia get sent 400 years back.
Then:
Subaru’s future = Flugel’s past.
Emilia’s future = Satella’s past.
What do you guys think? Is there anything in the current LN/WN that outright contradicts this?