Eurydice's "By Rook or By Crook", Spike's a hitman assigned to kill Buffy, awesome, mirrors canon...it's at Elysian Fields and Nocturnal Light.
Ashlee's "The Human Condition" is not strictly mob, but it's close...I love this... It's googleable, just append "spuffy" to the search sorry, am in a rush and not able to post the linkies
Greyangel's LA Nights (here on SR) has been posted before, and that's quite moblike...her "Winter's Tale" fits the mob bill exactly but I don't know where to find it, long time since I read it.
There's a story here on SR where Buffy is a ballerina and becomes Spike's wife/fiancee as payment to Spike for Hank's mob debts...I think it's a WIP |