Once, Diluc Ragnvindr and Kaeya Alberich were brothers--and the closest of friends. Now though, their relationship is in shambles and it doesn't seem like things will ever change between them. But when Diluc discovers some Abyss Mages are plotting against him and goes to stop them as the Darknight Hero, he gets caught up in a bizarre ritual that leaves him...As his thirteen year old self?! After finding out that the once-again thirteen year old Diluc has none of his adult memories and is back to his long forgotten bright, naive, and optimistic self, Kaeya attempts to start their brotherly relationship anew. OR: Diluc gets de-aged and Kaeya uses this as an opportunity to fix their relationship. (Title from "Two Birds" by Regina Spektor)