I found what is possibly the best Snape/Lily fic of all time. It's called The Moment It Began, and you may have heard of it, since it has over 5000 reviews. I would say it's sort of a mix of A Life Worth Dying For and Always and Never (which was renamed to The Difference Between Us), because in it, Snape is offered another chance at life after he dies, since he deserved it for being so brave. (Like ALWDF) And he's sent back to the day of his worst memory, where he makes sure that he doesn't call Lily a Mudblood. (Like TDBU, obviously.)
It's only rated T, so it's appropriate for everyone (I mean, if you can't even read T rated fics, you shouldn't be on this blog). And it's finished, which over 100 chapters. There's also a sequel, called The Moment It Ended. I love this fic so freaking much, because it's so well-written and I really love to think that Severus got to live his life over again. If my fic someday becomes as famous as this one, I will die happy.
If you love Snape, there's really nothing keeping you from reading this. Even if you're not a Snily shipper, read it. You will become a Snily shipper after reading it.
*After having your happiness drained by Dementors on the Hogwarts Express...*
Read this fanfiction, you'll feel better. http://www.fanfiction.net/s/3735743/1/The_Moment_It_Began