It's all florahart's fault. She committed a very fetching Snarry limerick, which made me think.

In her limerick, Snape picks up on men, blows them, and then records the memory in a pensieve. And the casual way she works this in made me realize that ( pensieves must feature more heavily in wizarding sexuality than most fanfic acknowledges )

( info about this is under a cut, for those who consider trailers a form of spoilers. I don't, myself )