I'm not sure if you're a fanfic snob, or how much of one you are, so it is with only a slight hesitation I offer "Of Corridors and Moonlight," (http://www.fanfiction.net/s/3319543/1/Of_Corridors_and_Moonlight), slight because there are a couple of things about it that I think should have been done differently. It's also a bit heavy on the angst in places, but then it's Snape/Lily.

"Painless" (http://www.fanfiction.net/s/3413258/1/Painless) is a half-crack half-serious Snape/Lily fic.