I've ran a search and came up with nada, so hopefully this won't be a duplicate request. =)
Things I remember:
1. Three artifacts ... Spike's is a big sword that they find with Angel, Buffy's is something she wears and I can't remember what Dawn's is (knife maybe?).
2. Spuffy is bonded and when Spike goes to test traveling a different dimension (that he gets to by Dawn opening it and Buffy's blood in his body) the bond is cut off. Spike is there for like 3 weeks but it's only a few minutes or an hour or so for Buffy. It's hard on both of them but of course harder on Spike. Anya is really helpful since she has a lot of knowledge about different dimensions.
3. They (Spuffy and some Scoobies) have to go rescue Dawn at one point and when they're there they devolve into their demonic natures, relying more on instinct than thought. Buffy ends up with markings (that Spike later draws for Giles) and fangs.
4. Spuffy is immortal. Dawn isn't once she has a daughter? The epilogue has them talking about her death and how she was ready to go and pass down the power of the Key to a new generation. Think she was over 200 at that point.
5. I'm pretty sure there was some kind of prophecy ... cause isn't there always?
6. I'm not sure what season it was based in, but one of the artifacts is found because Anya and Xander are getting married (Buffy's artifact), so around then. Plus Angel is in LA and Dawn exists.
I remember the story pretty well actually, but I cannot find it for the life of me. It's probably right in front of my face and the description just isn't tweaking for me, but I've been looking for two weeks now.
Thank you for your brainpower and memory in advance! | 
