Based on a tumblr headcannon about the Room of Requirement but expanded into a story. It has Helga Hufflepuff and Rowena Ravenclaw interacting and being a brotp, I'm not sure what more you could possibly want from a Founders era fanfic.
So how did the Founders decide how to do the sorting using the Sorting Hat?
When a strange girl shows up in the middle of the Final Battle, how exactly will that affect the outcome? AU, rated T because of some concepts and character death