Reina Natsuki is the older sister of Subaru, who was taken to the world of Re: Zero 12 years before the story's start, two years before the attack on Rem and Ram's village. Having met a beautiful platinum-haired woman who took her in, will Subaru be able to rescue his sister from the clutches of the Witch Cult? Or will his sister forever be lost as the Sin Archbishop of Pride?... more>>

Or What if Subaru had a sister that was transported 12 years before the start of the anime and becomes a Sin Archbishop?

This novel is already on another web and I'm just trying to get into the Scribble Hub.
https://archiveofourown.org/works/34386355 <<less

Subaru was destined to be summoned, but he never appeared. Instead he was replaced with Leo Borealis, a man who once terrorized the world... more>> in his time. Now, however, Leo has been reset to his younger self, and with part of his memories eaten by Lye Batenkaitos, he now finds himself in an unfamiliar world with only scattered recollection of who he was. <<less