EzrahJovero
After the events of Book 8 (although the ending was kinda rushed, it still made me emotional), the Healing Hands were together again, living the lives their father had given them.
One day, the children learn clues about their pasts connected to a separate continent known as Remnant. Although the siblings didn't exactly need to remember their past, they agreed to explore that place just to understand what they were like before they became sickly.
Or... an AU where Ruby is Hræsvelgr, Eikþyrnir was a relative of Nora, Heiðrún was Weiss's twin, Níðhöggr was Emerald's sister, and Ratatoskr was Jaune's little sister and there's a whole drama of how they don't remember them.