I don't think I can say anything that hasn't been said before, but whatever :D
You're one of the few authors who, in terms of the time-travel paradox, can make me forget my non-understanding of this concept. It's so easy to get caught up within the paradox in this genre - and every time I read time-travel written by you, it sidesteps the paradox gracefully. Granted, the fact that the Salem Institute did have Harry Potter as a student doesn't work for me (because how can the past be changed? It's the future that lies before us to be formed!), but that's my thinky-thoughts about this subject taking over. Everything else I don't object to at all, which is much more than anyone else would get from me.
I very much enjoyed your vision of a grown-up Harry and how the knowledge he has changes the world he's thrown into. I love how he influences Severus in a different direction; and really, it is inevitable that Severus would fall for Harry, isn't it? The boy has known too little kindness as is in his life, so it's logical he'd fall in love with the first person who does show him that. We've seen it happen in canon with Lily, after all.
Er, I forgot the other points I wanted to make. *major headdesk* I shall blame the sickness. Let me just assure you again that this fic considerably brightened my day, and I'm sure I'll gladly return to it to satisfy my time-travel needs in the future :)