It was human/AU. Spike was a detective and Faith his partner. They were after a serial killer who left a rose at the scene of the murders. Only Spike and Faith knew about the rose. Xander was a clairvoyant or medium who came forward to help Spike. They fell in love. Willow and possibly Andrew were in the story. I remember Spike was surprised how much Xander ate!
Ring any bells? Thank you to anyone who can help, I would really like to re-read and hopefully complete the story.