In Re:ZERO -Starting Life in Another World, Subaru IS Flugel: The 400-Year Loop Theory
The biggest conspiracy of Season 4 centers on the Pleiades Watchtower itself.
When Subaru finally meets Shaula, she doesn't just recognize him. She worships him as her master Flugel, the Great Sage who disappeared 400 years ago during Satella's sealing. She claims she knows his scent, even if his face is different.
Fans now theorize this isn't mistaken identity. Flugel had Return by Death too. The theory goes: Subaru didn't get summoned from Japan to the present. He was originally summoned 400 years ago as Flugel, lived through the Great Calamity, helped seal Satella, then died so many times that his checkpoint finally reset to the "present" timeline.
Evidence? Shaula only recognizes Subaru after he dies several times in the dunes. The "scent" she smells is the Witch's scent that grows stronger with each death, the same scent Flugel would have carried. Even their personalities match: goofy, over-the-top, tactical, obsessed with impossible tasks.
If true, Season 4 isn't just Arc 6. It's Subaru confronting his own forgotten past.