What's Past is Prologue (смешанная)

The night before Quidditch try-outs in the Trio's fifth year, a mysterious magical accident takes place in the Gryffindor common room, transporting Harry, Hermione, Ron and Ginny back over a thousand years in time to a century of discord, persecution and tumult, where they lose their memories of their own time and become the Founders of Hogwarts.
When another such occurrence returns them to a time they can no longer think of as their own, Godric, Helga, Salazar and Rowena must defeat Voldemort and overcome the divisions within the school they founded, while simultaneously trying to uncover the reason for their time-travel.
Some elements have been borrowed, with permission, from the work of Wicked Witch of the North on fanfiction.net, who has since closed her account.