Thank you both so much for taking the time to help me. I really appreciate it.
Nina, you were right, it was "Trusting You by 'DreamsofSpike'. That was the one I was looking for. I guess I must have got a little mixed up in my stories, and my brain was trying to put two together. I read so many, sometimes it's hard to keep them compartmentalised.
Anyway, as I said, thank you both for taking the time to try and help me, and Nina, thank you for the answer.
All I can say to you, Peyton, is: I hope you don't have a fic stuck in your head now that you can't think of! If you do, I accept complete responsibility, and offer my sincere apologies!
Thanks again, guys.