Following that altercation, Addison has to explain to Chief of Surgery Dr. Richard Webber that Mark is an old friend, a plastic surgeon and, oh yeah, the guy she cheated on Derek with back in New York. Webber approves of Derek's punching Mark once he knows the backstory. After they leave Webber's office, Mark runs down the hall after Addison, whining, "I lost my best friend! I miss you!" Waaaah, nobody feels sorry for you, McCheaty. Hey, I bet you can still catch up with Meredith!
Naturally, Derek and Addison hash out their problems in an elevator -- Addison explains that she had nothing to do with Mark's appearance, and then Mark gets on the elevator and Derek gets out. Mark chides his "best friend" Derek for withholding forgiveness, but no sooner have the doors closed than he is making his move: "Your marriage is over, Addison. All you have to do is admit it." Right message, wrong messenger. Mark invites her to meet him at the bar across the street; Addison, to her credit, does not go. (That's not actually clear from this clip show, but I thought I should tell you, since the People editors didn't speak up for once.)
We see Addison at home (and not at the bar), and we hear, and then see, Meredith complaining to Cristina, "She's got my McDreamy…she's got my McLife!" And what a paradise it is. The next morning (I think), Addison offers to walk the dog (really Meredith's dog), all, "I'll do it! You sleep," and her grateful husband is happy to take her up on her offer. Except, she suddenly decides that it's a good time for her and Derek to "talk." This is one of the very few moments I ever felt sympathy for McDreamy, because that is annoying, yo. If she had the divorce papers handy I'm sure he'd sign them on the spot.
The dog-walking leads, of course, to the delightful poison-oak-on-the-vajayjay plot, and we get another look at Kate Walsh's masterful itchy-crotch walk past all the interns, followed by Chandra Wilson's priceless reaction once she gets Addison in the stirrups. The exchange between Dr. Bailey and Addison ("You have poison oak…where nobody wants to have poison oak." "I slept with Mark a year ago, and apparently this is what I get!") is intercut with footage of People editors paraphrasing what has just been said. "If there was ever a case of karma…" observes one Julie Jordan (do you think her coworkers tell her she's "a queer one"? Because I would. At least once a day. I'd probably sing it, too). "The fact that it's a rash where you really wouldn't wanna have a rash just makes it all the more fitting!" That's the kind of deep insight that keeps People in circulation.