Stargate: Atlantis
Pairing: McKay/Sheppard
Rating: NC-17
Warning: non-con / questionable consent
A scene that stuck in my mind because of this.

Mark
by Night Spring

One moment he was coming into John's mouth, caught between the finger jammed up his ass and the firm suction of John's tongue, and the next, he was face down over the bed, ass high in the air, and John was pushing into him with one hard stroke, thrusting in and out in brutal rhythm as Rodney gasped for breath and tried in vain to brace himself, and as John came with a few final jerks and collapsed panting against Rodney's back, Rodney thought how the scrape of John's pants would mark his bare ass.