"And It Shall Come to Pass" by Rari Coss
I was just re-reading And It Shall Come to Pass (B/G - FRAO) by Rari Coss yesterday, and, man, is it smokin'! A neglected Giles is forced to submit to Faith's lunacy when Travers has her invoke an ancient spell that binds the two of them together forever. Yikes! Faith is evil, and Buffy is desperate to rescue and reclaim her watcher. Take a few minutes to read this one again--it's well worth it.