Twilight Sparkle’s been having extremely troublesome nightmares. Princess Luna steps in to assist.

(Found a new image, if it's yours let me know and I'll attribute properly.)

(Marked for sex, and gore in a few spots later. Not every chapter will have explicit scenes, but the ones that do will sometimes be quite explicit. There's going to be a lot of awful stuff, but the most extreme things will probably have somewhat skippable chapters, and any fetishes beyond basic BDSM or sex will have markings. Don't say I didn't warn you, because I did.)