It's the fictional Stephen Colbert; I don't know what your tolerance for RPF is, but although he's a character, about half the people he interacts with in any given fic are going to be real.

Some of this has come up during canon: there's a sexual experience referred to here (I actually made a mix for that pairing, over here), and he gets ordered around live on-air here (the actual action doesn't get very sexy, but the dialogue - "You can call me Sir!" - is all about the power exchange).

In terms of fiction, the best example I can think of is Running, and even that takes place after the dub-con, when our sensitive and understanding hero comes to his rescue. There's a remix challenge going on in that community right now, though, so I'm totally doing a version of that story which goes into the backstory more. (If I may toot my own horn a bit more, the issue also comes up in my very long State of Grace, although there again it's mostly about him getting over it and coming out with a healthier worldview.)

There are also a bunch of locked D/s stories in insomniacures, several of which feature character!Stephen being taken advantage of by various people. These definitely get sexual, and I recommend the lot.

. . . not a very impressive link list, I know. We've got huge variety for a tiny fandom, but we really need to step up to the plate re: the incredible dub-con opportunities here.