I read this awhile ago, and I don't remember much...it was definitely Buffy/William, they fell in love and by the end William had integrated Spike. Not sure if he just recovered his memories or if it was more magical. Pretty sure they were living in London at the end. I know this is vague - help much appreciated!!

Could it be "Believe In Forever" by Evenstar?

Is this the fic where Spike's demon is put to sleep by a spell that was meant for Angel? Since Spike's demon is asleep William is the one that is dominant and he has no memory of being a vampire, Buffy shows ups and helps him to adjust, they fall in love and move to London, marry (or marry first then move to London) and Spike's demon wakes up after about a year.

I can remember all that but not the title or author! It's driving me crazy!!

Believe in Forever by Evenstar is the one I was thinking of - Thank you! I'm not sure when I would have ever remembered!!

No, Believe in Forever is great, but not the one I was thinking about...the one I'm looking for doesn't have the big transformation scene at the end, it's more subtle. More like Buffy looks at William and suddenly he looks more like Spike...

Please, in the future try to give more info in the subject line. it makes it easier to search.