Oh, well done! You write with a nice archaic cadence, and I love the way you manage the time-travel. Having Albus prepare the way for Severus is an excellent touch. There are so many fun elements: early Hogsmeade, the complicated medieval politics, the plans for the squid, the story about the origins of the pensieve. I also love the simplicity of the "secret" Severus has been sent to discover. A clever, original story.