LOL... thanks! I'm glad you liked the BDSM part. I've done it in RL, so it gives me a bit of first-hand knowledge that I can apply to a fic.
Also, as for Snape... my recipient likes any and all combinations of Harry, Draco, and Snape, and has a particular fetish for Snape giving his boys "orders" and controlling the action. It made plot-sense here, so that's how I could include it, but Harry/Draco is still my favourite combination.