I'm so delighted by this -- I haven't read Kidnapped since I was a kid, long before I actually moved to Scotland, where I live now. I'm definitely due for a reread, and I recall spotting the slashiness when I first read it (though I didn't know it by that name, I just remember feeling shaken down to my bones when I read certain lines of dialogue between them).

I'm just beside myself with glee at the idea of canon Alan/David and I'm going to have to go and see that production if I possibly, possibly can!