So, I got this story mostly written a good while back and I finally went back and finished it. It was inspired by a couple of mods for Skyrim. The first one was called Slaverun which added a questline involving some slavers setting up shop in Whiterun. You could join them and help spread slavery to all of the Holds in Skyrim or you could find yourself captured and enslaved. But if you managed to avoid being enslaved as a female character, there was a system where the slavers would still spread, in the background, every so many in-game days taking control of a new hold and instituting laws limiting what equipment you could have on (specifically any sort of weapons, armor or clothing) Flaunt the rules too much, or just attract the attention of the slavers and you'd soon find yourself wearing a collar instead.
Another one, I'm not sure which one it was, added random slavers traveling the roads of Skyrim, often dragging one or two captives along with them. It also added a bit where the slavers would try and capture you but, evidently being smarter then most bandits in Skyrim weren't about to fight fair. They'd try and sneak up behind you, get a rope around your neck and capture you that way. One time, I was playing the game and while traveling passed by a group of slavers escorting a short coffle. I was careful not to turn my back to them until I was well past the group, then continued along my way...which was when I ran into a bear. As I was still at low level, the fight took some time, but in the end I had managed to prevail. I looted the corpse, started healing up and was getting ready to continue on my quest...when the slavers who had caught up with me while I was fighting suddenly came up behind without my noticing them. Before I could react, they'd gotten the leash on my and my hapless adventurer found herself being dragged off with the rest of the captives to the nearest slave market...