If I have to be completely honest, I started off as a Snape/Harry shipper. I read fanfic even before reading the books! But when I got to "The prisoner of Azkaban", I went for Snape/Lupin. And after "Order of the Phoenix" (and "Snape's worst memory") I started shipping Snape/Lily. I didn't include Snape/Harry because I don't really ship them anymore.