Before, during, and after Alan Rickman’s portrayal.
What?
I do, a little bit – though it’s entirely Rickman’s fault. He even makes the greasy hair work… 
Well, it wasn’t a big deal…and then I saw the first movie.
Me! Me! Me!
Not necessarily for Snape, but Rickman is one of my favorites. I just bought Sense and Sensibility today and finished watching it a while ago. Though I am glad to be able to put his face to the character when reading the books too.
My wife does. She liked the character in the book but is now infatuated with Rickman’s portrayal. She has liked Alan Rickman since he played the Sheriff of Nottingham in that Kevin Costner Robin Hood movie.
Add me to the list. I had the “thing” a little bit before Alan Rickman and a little bit more afterward. I don’t usually picture him as looking exactly like Rickman, though, I realy picture Snape with slightly more sallow skin and a slightly more hooked nose… still dead sexy to me.
Then I started reading fan-fiction and just went off the deep end (yes, I still count it as a thing for Snape because I definitely feel that way about canon Snape, not just fanfics).
I adore Snape and Alan Rickman so the films are absolutely heaven for me. My next 3 films on moviesforme (canuck version of Netflix) are all Alan Rickman titles. 