This thing has too many "I think"s, "I believe"s, and "also"s, but I'm posting it anyway. And, remember, I invite you to play along! Feel free to comment, argue, point stuff out. :)

I got a request for additional ramblings re: Irene's motivations and where she's coming from with John, so here's what I think about that:

Her primary motivation, of course, is to play the game, to win, to protect her lifestyle and keep her power.

But I also believe Irene is genuinely attracted to Sherlock, physically and intellectually. I think she's also fully aware of the intensely committed relationship he and John have (sexual or not). Since Moriarty has also told her his nickname for Sherlock (The Virgin), she may think that gives her an advantage somehow, that she can offer Sherlock something that John can't. (However, in my opinion, she is *way* too overt with Sherlock as far as flirting/advances. Sherlock has eighteen thousand protective walls up and she's trying to blast her way through with a direct physical approach; I just don't see Sherlock giving in to it. But he clearly has some respect or affinity for her since he then presumably makes quite an effort to rescue her later in Karachi.)

As for how she behaves with John—I think she sees right away what John and Sherlock are to each other, and when she asserts to John that they are indeed "a couple", she means it in a non-sexual way, the definition that means, "you are joined, you are united, you are a pair." She cannot break them up, and she is … not exactly jealous. More like acknowledging an inconvenient truth. I think she sees that pursuing Sherlock is a pipe dream. And I actually think she tries to bond with John a little bit over it. You're drawn to him, I'm drawn to him, look at us both. And the bit about "I like detectives, and detective stories" I'm now thinking is a direct attempt of hers to tell John, "Hey, you and me, we're in the same boat, we've got the same weaknesses/kinks."

The warehouse scene is really pivotal for her and John, though. John is soooo angry with her. Why? Because her actions hurt Sherlock. And she *mostly* is honest with him. The only bratty bit is the "are you jealous?" line. But overall, she's pretty straight with him, and he's very straightforward with her ("I'll come after you if you don't", "Fine, I'll tell him and I still won't help you" and when she asks "Does that make me special?" he could have given her a petulant "No," but he says "I dunno. Maybe" instead).

And I think that might be a turning point for her and John. Because later, when Irene shows up asleep in Sherlock's bed, look at John's face. He's not angry. He's kind of amused.

And then the scene in the sitting room with the phone; Sherlock and Irene seem to have a moment, John makes the "baby names" crack, but I don't see any anger in it.

But later, it's very telling that John LEAVES HER ALONE WITH SHERLOCK FOR HOURS. And that they apparently talked about Sherlock's habits. Sherlock asks "Where's John?" and Irene says he went out a couple of hours before. Sherlock says "I was just talking to him" and she says "Yeah, he said you do that." Somehow, John trusts her enough to be alone with Sherlock.

So what does all this mean? My two cents is that John, perhaps grudgingly, accepts that Sherlock sees something in Irene. I think he also trusts that she has enough regard for or interest in Sherlock that he believes she will be loyal to him (which is entirely not true as she has already betrayed him with Moriarty and is going to treat him quite cruelly in the scene with Mycroft.) But she made inroads with John with that warehouse conversation.

I also think Irene has some level of regard for John, how loyal and protective he is of Sherlock. But Irene's also the type of woman who would steal your husband and shamelessly blame you for not being able to hold on to him.