It's one where Xander is taken over again by the hyena, but now it's permanent, and has kinda melded with Xanders personality. Xander finds Spike, boinks his brains out (Spike is hesitant, he's only really doing it to keep things... uhh... calm). The part that I remember most clearly, is Xander snuggles against Spike and says "mate" and Spike objects, but eventually tables it for later conversation.
Xander is pretty much trying to rebuild a pack, and wants Spike there with him. It's just smut, really, and as far as I know, it was a stand alone, rather short (I think under ten pages).
Any help would be appreciated.
It has been found! Thank you to any/all that tried to help! Credit goes to mygothangel for finding it. Story is located at http://spikedluv.livejournal.com/81483.html for any that wanna read it too.