Young Buffy seduces her boyfriend's father who's Spike

I read this on this site I think, and for the life of me can't remember the author or title. Buffy is having an affair with her boyfriend Angel's father (or stepfather). She's young in this fic, and Spike is married to Darla. I think Darla later dies and Spuffy relationship emerges. Think it was kinda angst-y and written as a series instead of a long fic.

Any help would be appreciated to bits!

Love/annie

Forgot! I distinctly remember a scene where Angel's sleeping upstairs and Buffy sneaks down to have some baom-chika-wow-waa with Spike. And some of the same on a staircase? If this rings any bells?

Sounds like the P-Series by Sotia
It is no longer available on line but if you email her she will happily send through a copy.
There is a note about it on her author profile page

Moving this to found.