Oh, fandom. Yeah, the term 'dub-con' is, I believe, unique to fandom, but the conept is a pretty common one across all kinds of pornography throughout its history. Fandom is a playground, a place to live out our sexual fantasies without consequences. Fantasies involving violence and rape are pretty common.

I think to me 'dub-con' is usually meant to imply that the party in question wants it on some level, or ends up enjoying it, or changes their mind midway through the act about wanting/not wanting it. It's kind of an insidious thing, since one might come to the conclusion that this makes it okay. As far as I'm concerned, dub-con and non-con/rape are flavors of the same thing. It's not my cup of tea, but neither are a lot of kinks, and I'm okay with it as long as it stays in people's heads and no one thinks it's acceptable in the real world.