Ho my! I saw the pairing, and I braced my self for teh nasty, but this is just wonderfully lurid and breathtakingly smutty, is all I can say. Great job with the contrast of their skin tones (Filch is probably the only one who'd turn out sallow and pallid next to Snape, the slant of the light from the window, and that glimpse of the lil' student in the crack of the door gives it an extra kinky boost. Love it!