Satin is the "kind of canon" offspring of Velvet and Cteno. It all happened after Cteno and Velvet had sex, only to find out afterward that Surprise had cut a hole in the condom. Strangely enough, though Velvet is a mare, it was Cteno who got pregnant. The proud parents called the little filly 'Satin'. Of course, Suprise doesn't mind babysitting from time to time.
Posts about Satin pop up from time to time around the blogs of Velvet, Cteno, Surprise or their mod's blogs.
OOC it was this picture, which Surprise mod Will quickly scribbled in answer to Velvet mod Carnifex' earlier work that started the idea of Velvet. Carnifex ran with it, and apparantly Cteno mod Slugbox reluctantly went along with it.