unknown xover: Buffy getting married

[ladyhatshepsut.livejournal.com]

Okay, I'm gonna try this again, this time with just the basics.  I think it part of a series, or maybe just very long.  The Scoobies meet a group from another fandom, one that can be just as violent as her people.  Might (or might not) be the X-Men.  Might me someone working as bounty hunters.  Buffy and male leader are getting married, big lavish church wedding.  Buffy and hubby-to-be have a run-in with baddies, either doing a bounty the morning of the wedding or opponent coming to the church just before.  I really hope someone recognized this, it really driving me crazy trying to remember where I read it, what fandom it crosses with, and who Buffy is marrying.  Logan?  Dom Toretto? Richard B. Riddick?