"Let's talk about the sex in Snape fan fiction. It's never vanilla. And it always features one or more of the following scenes: Snape initiating the woman into S/M play; the woman kneeling before Snape to perform oral sex..." and on and on about women fetishizing Snape's buttons, Snape bathing women and insisting they be clean before sex, etc. Snape's dom preferences are emphasized over and over.
Clearly I have been reading the "wrong" Snape fiction, as what het Snape fic I have read has involved: 1) McGonagall rather dominant over Snape, though not what I would call S/M play (and one perfectly delightful three-way with them and Dumbledore); 2) sentimental Snape/Hermione where Hermione had to persuade practically!virgin!Snape that (vanilla) sex can be fun; 3) Bellatrix on top in a rather D/s context but again not what I would characterize as S/M (oh dear, I seem to have written that myself); 4) Snape/Lily, which I skimmed rather than read, as it was sappy and the textbook definition of vanilla but did not appear to be the only one of its kind; 5) Snape/Narcissa where Snape and Cissy took turns topping but where the real or imagined presence of Lucius tended to complicate the dynamic enormously, even when Snape was dominating a given scene; and, though I have never actually read beyond the headers for this, 6) Snape/SomeMaleCharacterTurnedIntoAGirl!V
Millman makes brief mention of the existence of Snape/Harry fic based on dom Snape in Occlumency lessons (Snape/Lucius, Snape/Remus and the ever-popular Snape/Draco don't register here), and reminds us that bad men are Bad For Us, even quoting Rowling's legendary "Are you thinking of Snape or Alan Rickman?" (who gets mentioned a dozen times in the essay, particularly his voice; I get the impression the essayist really wanted to get Mr. Rickman's attention). But mostly it's about Dom!Snape/Hermione!Sue and What That Says About All Of Us. If I thought five sentences of Millman's analysis were accurate or fair to fans -- all female psychology being identical and such -- I'd have to cry. Fortunately, she doesn't get even that much right.
In better news, Barnes & Noble has The Making of 'The Hitchhiker's Guide to the Galaxy' on the bargain table for $6. No Rickman but plenty of Marvin! Oh, dominate me, Marvin! Spank my naughty buttocks! ...er.