I suppose with me it was that the first fanfiction I read was Severus/Hermione, and that hooked me. For a long time, I wouldn't read anything but them. I have branched out since then.

I still prefer him Het, although I don't like to read him with any other female except Hermione (I'm so singular, hell, I totally botched a threeway F/F/M story with them), but I can deal with him and certain male characters okay, but the rarer the pairing the better. Some of the common ones (Snarry, Snupin, Snucius, Snaco) I just can't read.

And I can picture him having some strange ideas about love, but if fanfiction can give second chances, I love giving them to him. As you say, he's seen through the eyes of a teenaged boy who can't stand him, so it's hard to know exactly what we are seeing.