I like this a lot, but the place it stops is giving me whiplash! It just suddenly ends with a surprise kiss. It cries out for continuation! What does Harry say, what does Severus think of the tale of the years he apparently can't remember, does his sudden submission to Harry's advances have anything to do with secret crushing on James... so many possibilities!
I love the hints of Harry's own crush: "his" Half-Blood Prince, eh? nudge, nudge? And his unquestioning following of Dumbledore's instructions without questioning what they really mean, just as he's been doing for years.