Jane A. Leavell:
"Music, Magic, and Mayhem" - gen, FRT, maybe FRM
This long story is an inventive and unusual take on Giles's past with Ethan. Once upon a time, Ethan did a spell that sent Giles and a friend to a strange place, where music is how one works magic. And huge things happened to Giles when he was there. Important things. Some things Giles has attempted to forget.
Now, it's years later, and Giles is living in Sunnydale, the quiet respectable Watcher and businessman. But Ethan reappears with an agenda, and also with Willow in handcuffs. Ethan sends them both back, and Giles is none too happy about it. What happened back then?
Read and find out.