A bit late to the party here, but eeeeee, I love this! :D You've made this unlikely pairing work so damn well. Sirius' thoughts about Minerva and his gradually changing view of her is lovely. As is the way she only resisted him a bit before giving in to him. It makes sense for her character as you've portrayed her here: soaking up the simple pleasures shamelessly. My favorite bit is this, I think:
"Take it down," he whispered. She ignored him, but when he dug his thumbs into the arches of her feet (after letting out the most delicious moan) she looked straight at him as she unbound her hair in one practiced movement.
"Fuck," he muttered, as a cloud of rich, dark, silver-streaked hair tumbled down and spread over the red leather cushion.
"Did I tell you to stop?" she said, and raised an eyebrow at him.
"Take it down," he whispered. She ignored him, but when he dug his thumbs into the arches of her feet (after letting out the most delicious moan) she looked straight at him as she unbound her hair in one practiced movement.
"Fuck," he muttered, as a cloud of rich, dark, silver-streaked hair tumbled down and spread over the red leather cushion.
"Did I tell you to stop?" she said, and raised an eyebrow at him.
Hee! Really nice story. :)