I loved this! I have a thing for time travel fics, and teacher/student fics, and hot boy sex . . . and damned if you didn't deliver it all wrapped up in a wonderfully written story!
I adored your Severus, and absolutely loved how you worked all the other characters around because of one or two small changes in the time line. It really is amazing how different he became (with out loosing his innate Snape-ness) just because he had someone who took an interest in him.
And the wooing :-) Who could not love the wooing! Even as a Ravenclaw, his Slytherin still came out.