Interesting idea you've got there. I've only ever been a fan of Lily/Snape fanfiction when it came down to the idea that Snape will forever be pining after her, but of course, Lily had other ideas. I've always felt bad for Snape, except in SS/PS when he was being such a git to Harry. Anyway, nicely written, but you should consider putting just commas at the end of each line. For some reason, it looks a little choppy with periods.
The simple truth is that authors like making people squirm. If this weren't the case, all novels would be filled completely with cute bunnies having birthday parties. — Brandon Sanderson, Alcatraz Versus the Evil Librarians