I was in love with it right from the opening paragraphs, which were stylishly done, and then the whole introduction of Snape as Spider, as an Elder Geek of some repute... love, love, love. Then I was drawn in by the gradual revelation that this AU has a direct relationship to the actual HP universe--oh, so intriguing! I was IM'ing a friend at the first "incendio" to say: "I. Love. This. Story."
I IM'ed her again when I got to the twist about Sirius and Remus being the godfathers. This is a bona fide Snarry classic as far as I'm concerned.
The sex was meltingly hot, the isolated and emotionally stunted Snape is perfect, and I just... yeah. Off to write recs for it in my LJ, IJ, GJ, JF, and whevever else I can think of...!