Spike turns Buffy and is her Master/Mate

[mlawson1.livejournal.com]

Looking for a fic that I'm pretty sure I read on TSR, but haven't had much luck finding it. I don't remember much, but I do distinctly remember that Buffy is changed by Spike who then becomes her Master/Mate. The sleep together and the story mentions that it was a Master's right to "break in" their Childe so that the Childe "fits" only their Master. It was a sex scene, but that's all that I can remember. Any clue?