This is such an interesting topic and I'm going to go away and give it some more thought. In the meantime, I thought I'd muddy the waters a bit and slip in an observation which I've made and that is: I wonder why it is that I and many people I know *hated* the idea of AUs when they first began reading Pros and then ended up accepting and enjoying them to the extent that many AUs have become firm favourites e.g. Harlequin Airs (though if I remember correctly Bodie's in Ci5 so it's semi-AU); Cook and the Warehouseman; Suitable Gravity; The Secrets Beneath; Professional dreamer; Arabian Nights; A Birdwatchers Guide to Cornish Ghosts. When I first took a look at Pam Rose's Arabian Nights I couldn't accept the idea of the Doyle she'd created but much later, looking again, I read it, loved the whole story and have since read it about 3 more times and it's now one of my top favourites. Anyway, just thought I'd mention it......... what was the orignal question, again?