Fic: Sirius-ly (sirius & Lily)
Dont worry its not a sirius and lily paired together fic, its just like some friendship development between the two. I think they would have started off with a rocky friendship but it would grow into something better. Plus theres some James and Lily fluff :)
also if you ship Sirius and Marlene you may or may not like this.
http://www.fanfiction.net/s/9406066/1/Sirius-ly