Pairing: Rosmerta/Sirius Black
Fic Title: Semi Charmed Life
Why This Must Be Read: Long, plot driven good fics that center around a minor pairing are a very rare find in fandom. The thing with minor pairings is that the author has to go the extra yard to convince the reader that these two characters could possibly work together had things in canon gone a little bit differently; or, in a case where canon is silent on a character's romantic history (like Sirius and Rosmerta) that the pairing can fit in the time line of the existing story. Semi Charmed Life not only makes you believe in the pairing, it also has a lot of Marauder action for MWPP fans.