Hehe, I don't like many threesome pairings, but I could enjoy this one.
Cath stated in last week's ep. "I don't like pain"
That's true, but there are a few things to keep in mind, I think. The first is that sometimes when people say they hate things, they don't really mean it. Plenty of people make judgements on those who enjoy BDSM. I don't think most of the people who like BDSM would admit to it. Especially not in the work place.
In other words, she could be lying.
It's interesting to note that both Grissom and Catherine seem more open about their feelings on BDSM around Lady Heather. Catherine says she doesn't like pain, but around Heather, Cath has said that being likened to a dominatrix is a compliment. Grissom has said that he thinks women with ligature marks is crossing a line, but at the same time, he is incredibly intrigued by LH and the role of a submissive, etc.
Both have expressed an interest, and so perhaps with the right circumstances and with a person they trust (example: Heather), they would test the waters. Even if neither like pain, that's okay. That is only one aspect of BDSM. Grissom, in particular, seems to be fascinated with the idea of control, which is another part of BDSM.
Our threesome could have a fun evening together without any pain at all. Or sawdust for that matter. :lol: Not to mention, Heather has shown that she is more than a dominatrix. Who's to say they couldn't have plain, vanilla sex? Well... as vanilla as one can get with a threesome.
It goes without saying that this would never happen on the show. CBS would FREAK. OUT. if they saw that in the script. But I think that the writers have laid enough ground work that, with a skillful fanfic author, it could be believable in a piece of fan work.