I am very impressed with this story. While I have read a few stories that include BDSM, they rarely go into the psychological aspects of the partners imo. The characterizations you're expressing are very believable, and very compelling. As things stand, I can allready see the trust building in Severus, even though he knows who she is and he does have some doubts about her, he is willing to explore via her instructions and accept her as a dominate partner - and we do see that though he has accepted that she will not engage with anyone in intercourse, I'm thinking he does wish for it at least on a very sub-concious level.
(When I try to lick that delightful curve just above the heel, she puts her foot on the floor and offers me the other one, giving me a glimpse of a blue, lace-clad heaven I will never know.)
I am anxious to see how his imposed "vacation" will affect him, what his thoughts and feelings will be once he no longer has Hogwarts to restrain his psyche into a "this is the way to act" type of scenireo (pls excuse my spelling, never one of my strong points). Ok, as I'm babbling now I'll shut up and watch for more! Thank you so much for sharing this story!