There's not a whole lot of levity this week, other than Mark having a patient who wants some Kardashian-sized butt implants. Lexie thinks she's doing it for a guy (and finally lets out some of her own issues with regards to what happened with Mark, although only for a moment) but when she and Mark talk to the girl, it's clear she's just totally doing it for herself. All's well that... ends well! I'm sorry, I couldn't resist. But Mark and Lexie seem to be starting up some tentative flirting again, so yay. But while his patient wants this change for herself, Mark realizes that Callie is doing the equivalent of getting a boob job for a guy by going to Africa. She's actually quite a jerk to Arizona as they are finishing up packing and getting ready to leave, and it's more and more obvious that her heart isn't really in the move. Mark finally calls Callie on it, and she says that she knows, but she loves Arizona and is doing it for her. But when the two women are at the airport heading to their plane, and Callie can't help but still be kind of passive-aggressive about the whole thing, Arizona finally snaps and admits that she won this amazing grant and can do exciting things but that Callie is ruining all of it for her. They have a standoff, and the result is that Arizona tells Callie she doesn't want her to come along after all. Callie threatens that if she really does this, they are over, but Arizona rightly points out that as they are screaming at each other in the middle of an airport, it seems to be over already, and she leaves.

Owen is doing his own thing for the day, running a trauma clinic for the residents as part of winning the Chief's contest a few weeks ago. He sets up a mass trauma situation with nearly 30 dummies in the parking lot that all have horrible injuries, divides the docs into teams, and has them get to work fixing their "patients." Everyone gets frustrated pretty quickly because Owen keeps thinking up imaginary wrenches to throw into the imaginary situation, like the medical helicopters never arriving, and slowly all of their mock-patients start to mock-die. Jackson, Alex and April are on a team together and after it starts raining and shit keeps going wrong, Jackson just up and leaves. April and Alex keep working and eventually, April goes kind of nuts and starts screaming at Owen about what is going to happen, making up her own situations to match his. It's kind of insane, but shows she might be a good trauma surgeon one day. Afterward, Owen goes after Jackson who tries to play the "I lost friends that day," card to excuse his behavior, but Owen has him beaten thoroughly by having been through actual war, and he puts Jackson right back in his place saying that losing people isn't an excuse to act like this. Jackson seems to finally realize that he's right, and he goes back to his own trauma training.

Bailey has the sad task of helping out with Mary's autopsy, not because she has to, but because she's desperate to figure out what went wrong. Anna Draper from Mad Men is the pathologist and she's much less endearing here than she is in the 1960's -- as she works she seems more concerned with fixing some botched dinner reservations than figuring out what is wrong, and Bailey's cookies are good and frosted about it. It's a bad combo of Anna not being emotional at all, while Bailey's emotions have taken her over. Sadly they can find nothing wrong, though they can't test Mary's brain for another two weeks because [insert technical medical explanation here]. Bailey goes to gripe to Derek about it and while he sympathizes, he admits that Anna is right and they have to wait that long, much to Bailey's distress since she's not sure how she's going to really face Bill and tell him they have no answers about why Mary died from a simple surgery. Derek, meanwhile, spends the whole day in a conference room trying to write a grant proposal to start up his Alzheimer's clinical study, but he can't actually figure out anything to write other than, "Alzheimer's is bad, y'all." Bailey is the one who points out that he's too consumed with worry about Meredith possibly coming down with the disease to actually focus on the proposal. Derek realizes she's right, and though Meredith wanted to take part, he tells her that night that he can't work on it with her because he'll just see her there and only think about the what ifs rather than get any work done.

It's the second blow of the day for Meredith -- the first being that Cristina unloads on her that she thinks what happened to her is all Mere's fault. Cristina has to spend her day looking after Roy, because the lungs that she won him a couple of weeks ago have finally become available so Teddy goes to pick them up. Cristina's pretty freaked out but manages to do what she needs to do when all sorts of complications arise as they wait for Teddy's return. Owen releases Meredith from the trauma exercise so that she can go help out but Cristina is totally cold towards her, which seems weird since they were getting along fine until Meredith called her a hero last week. I guess somewhere between now and then, Cristina decided that it's Meredith's fault that she kept operating with a gun to her head, because Meredith was begging her to save Derek and offering herself up to be shot. It's slightly shaky logic, and Meredith argues that Cristina wouldn't have let someone die no matter who it was on the table, but Cristina's mind is made up. It's compounded by the fact that Cristina is completely livid that Meredith seems totally okay now while she's still a complete mess. Teddy finally gets back with the lungs and Roy is saved, thanks to Cristina's work, but she realizes that she's had enough and goes to the Chief and quits. She seems quite satisfied with her decision when she tells a shocked Owen what she did, but it will be interesting to see how long it lasts.