Teddy, meanwhile, has finished up her surgery and arrives at Mark's to find the door unlocked. She heads in and calls hello, then starts telling him about her bad night as she strips down to her own skivvies. She walks into the bedroom and stops when she sees Reed in the bed, and the resident pulls the comforter up to her eyes as Mark walks out of the bathroom clad only in a towel. After an awkward moment he tells the ladies that this could be fun... if they all decide to let it, and then grabs at his towel and I swear I thought he was going to rip it off dramatically. He doesn't, though -- just leaves it up to the ladies, and Teddy is pretty aghast when Reed shoots her a look that at the very least, isn't ruling out the idea.
As Mere and Cristina arrive at the hospital the next morning, Mere glumly repeats that Cristina is thinking of moving in with Owen but Cristina happily corrects her that she is doing, not thinking. Mere turns super-drama-queen and starts shuffling down the hall with a nauseated look -- It's totally the picture of discretion for someone who has been told not to say anything about what may or may not be going on. Cristina of course realizes something is up and tells her to spit it out, so finally Mere admits she thinks there might be something going on between Owen and Teddy. Cristina laughs it off but Mere, in her best Eeyore impression, says she's pretty sure. Of course when Cristina asks her why she thinks this, Mere finally draws a line and says that she can't say, but Cristina should think about it. Really, Meredith? You told Derek you wouldn't say anything so your answer to that is to totally say something, but not to say enough to make it worth it for totally ruining your friend's day and possibly her relationship? I'm not saying Cristina shouldn't know what happened but come on, either tell her or don't -- this is just gross and selfish. Cristina in fact calls her out on that, but Mere can't handle it and runs off while Cristina assures her they aren't done.
Teddy is telling Arizona about what happened and they have a good laugh at Reed's expense for not dismissing the threesome idea, though Arizona points out that it might not have been so bad and fairly accurately calls Reed a "brunette surgical Tinkerbell." Lexie has been listening, disgusted, and Cristina is there as well, so her antenna goes up when Owen arrives and asks what they are talking about. When Teddy tells him he turns all gruff and alpha male and says angrily that Mark cheated on her, but Teddy tells him they weren't exclusive so there was no cheating. While she does seem a little bit bummed, she honestly seems pretty okay about the whole thing. Arizona runs off to see a patient and Owen offers to say something to Mark but Teddy just laughs at him and tells him he doesn't have to defend her honor. Cristina doesn't really seem worried even though she's been paying close attention, and she and Teddy go off for rounds.