I live this story and your concept for it. I think how you have Snape and Hermione play off each other is really well done, brava!
This is one of the few stories that stick out in my mind and that I continue to come back to to reread and check on updates. Really interesting concept and very well done!
I'd like to make a bit of commentary, While I love the story (and I do) I think the entire time you don't represent Hermione very well. She is very much the brightest witch of her age and you show her as not being able to remember a simple bubble head charm. she could more than challenge snape on an intellectual level and though he would confound her to a point she would not be completely lost as you portray her in both a magical knowledge sense and in the sense of mentally sparring with him. Other than this your ideas were sparklingly kinky and your wordplay was witty and refreshing. I just had a bone to pick with how one of my favorite characters was ...for lack of a better term dumbed down.