Edit: Desaturated Twilight and Spike's colours as per suggestion
From the fanfic "Sunshine and Fire" which, admittedly, I haven't finished but I liked the chapter where Twilight and Spike are trying to find a way out of a desert... in a land where the sun never sets and they could be lost for "days" under an eternal sun... in a land where shadows are magically banned and so there isn't even any shade. It was very grueling.
I tried to shade it in the way I've seen other people shade really warm pictures, with a high contrast to it, but I don't know if I succeeded or not
Anyway there you go.
Fanfic is here: [link]