Wait, have you not read the last book? Because that's where he was truly redeemed (in my eyes at least.) In ways i can't explain without total spoilery

No, I've read them all, but I'm rereading from the beginning. And I only ever read them each once, as they came out, so most of the details are pretty fuzzy.

Wait, have you not read the last book?

That is a key question, because it does address Snape's backstory and motives in detail.

And I'm trying to figure out why he's so popular, when at this point (three books into the series), Snape has been consistently a dangerous threat to the protagonists, and if not evil, at least completely misled. Because at this point, we don't know any of his backstory other than that he hated James & the others. So why the fannish love?

Because he's flawed and damaged and people like the broken teacup characters?

people like the broken teacup characters?

Too true, but there's quite a gulf between Snape and Rodney McKay, or even Snape and Alex Krycek. (Nick Lea, for one!)

And I only ever read them each once, as they came out, so most of the details are pretty fuzzy.

Well, when Harry receives Snape's memories in the last book you do understand how tortured Snape's existence has been. That he's both arrogant and filled with self loathing. That he's been very honorable (though mean). That he's been true to the one thing that mattered to him (Lilly). That he's very bravely endured incredible trials because of his promise to Dumbledore.

And while I think that Snape's actions in the earlier books don't necessarily indicate all this, JKR does drop hints. Particularly when Harry is studying occulemency and receives the memory of Snape's humiliation by his father.

But again, in Snape's mind, that all led back to Lily and Snape's idea of his worst day being his "MUDBLOOD" hollering at Lily and ruingin any small remains of their friendship, prior to his buddying up with the Young Republicans Deatheaters, not necessarily the embarassment caused by James.

People are also convinced that Draco is a sympathetic character.

I don't see how Snape's morality trumps Krycek's, though.

Oh, I totally feel bad for Draco in book 6, especially. Is that different than being a sympathetic character?

I always liked Harry's realization that his father, of blessed memory, really could be as shitty as any other teenaged boy. And I liked Snape for the realization that someone who despises you is not necessarily your enemy. It's a very useful shades-of-grey lesson for young readers.

He's not supposed to be screaming at his students, or taking out his own childhood traumas on them.

Seems to me that Snape would have fit in well among the faculty at the College in Kipling's Stalky & Co.