Right after unlocking her aura, Ruby received visions of an imprisoned person atop a glowing yellow tree. Something urged her to follow it, to help that person and so she decided to do so. She got out of her house and followed the light, only to die a few moments later to a pack of grimm... Set in Remnant with Darksouls-esk features, the land between exists separately.

Just a little one-shot idea I cooked up after finishing my first playthrough of Elden Ring. Basically, Ruby Rose fell into the Lands Between after the finale of Volume 8.