Silence runes work better with closed doors

AU. Offshoot of Harry Potter and the Boy with Red Eyes. Furious Black and Hermione Granger had been together for awhile. When the need for alone time leads the two of them into an empty classroom, what happens when the door isn't shut all the way? Oc X Hermione, Oc X Hermione X Lavender B. Contains voyeurism, threesomes and slight ron-bashing. You've been warned.