I like that you jumped right into the main plot device. And I loved young Snape's voice here and how Harry could not let it go. I liked the whole concept surrounding page 447, kind of like time travel only better, very clever. Oh and Snape was actually heart-broken when Harry didn't write back! That first detention was wonderful! Young Snape and adult Snape matched perfectly. I like the way you tied everything in with canon. I absolutely loved the depth of Snape and Harry's relationship, even without a bunch of fluff. A marvelous story, indeed!