Here on a rec from chiralove. Loved all aspects of this! It's funny how your comment consensus seems to be that we all love Godric/Salazar the best... for me it's the language shift you use, and also the way their magic seems both stronger (building Hogwarts) and more primitive (cauterizing a cursed wound) than what we know in the Hogwarts modern era. And Salazar gets big huge love in my book for being the reason Snape gets saved. =) The sadness and loneliness of the Harry/Severus parts comes through well, without you having to beat us over the head with the fact that they're SAD, and also LONELY. And the Al/Scorpius parts have a playfulness to them that fits teenagers who think that studies and love affairs are both just a big adventure waiting to be explored.
This one's going into my bookmarks, which is a real compliment since my HP bookmarks are mostly classics like Irresistable Poison, Transfigurations, and Parseltongue-tied. Brava!