So in a fit of I don't know what, Owen asks Cristina to move in with him, using the totally unromantic "my shrink thinks it would be a good idea," but he does sound excited and Cristina, drunk at a party Derek is hosting, totally agrees. She's totally stoked about it, so Mere and her Death Glare of Judgment decide to drop the bomb that she's suspicious of Owen and Teddy. Unfortunately, even though she's already said more than Derek ever would have wanted, Mere decides to stop there to keep his secret, and refuses to give a now freaked-out Cristina any specifics. I hope she managed to make herself feel better, because she basically managed to muck everything up enough to get it off of her own conscience while selfishly not following through. Cristina watches Owen and Teddy as they work together throughout the day but with a lack of anything concrete from Mere she seems willing to believe the best even though some little doubts are obviously creeping in to her head. It doesn't help that their patient is an old man who hears the voice of Callie's patient and recognizes her as the best friend of his (now dead) wife, who he fell in love with 50 years earlier on the eve of his own wedding. Having to spend the day watching a couple admit they should have married each other when they had the chance instead of doing the right thing certainly isn't helping Cristina cope. Mere at least finally tells Owen that he needs to sack up and admit what he did, and he does, and it doesn't go very well, so that whole moving in together is postponed for now.
In happier couple news, Lexie and Alex are acting all super cute together and she finally admits she wants to know what they are, so Alex says that they are a "thing," much to Lexie's delight. He admits later to Mere that he's "being a duck" -- he's walking and talking like a duck because that means that he'll probably become a duck, or rather a good boyfriend. All is well and good until Mark, who hooked up with Reed and got caught and dumped by Teddy, has his eyes opened for him by Callie, who points out that he obviously still loves Lexie and she still has feelings for him, so he should do something about it. He finally tells Lexie he's still in love with her and wants to marry her, and though she manages to squeak that she has a boyfriend and sticks with Alex for now, she's obviously shaken and unsure. It's going to really be a bummer for Alex, who is not only trying to be a good guy, but also had an amazing patient save with the help of Lexie's photographic memory and seems to be in a more positive headspace than he's been in forever. Demi Lovato, playing a teenage paranoid schizophrenic, is brought in to the hospital to be committed but Alex feels like something is missing and does a bunch of research, including having Lexie search the Lexiepedia for something that might match all of the girl's symptoms. It turns out she has some super rare hole in her inner ear that's been causing all of her problem, Derek operates and fixes it, and she's now a normal teenager, all thanks to happy and surprisingly well-adjusted Dr. Karev.
The remaining docs are all also involved in relationship drama -- Callie and Arizona are broken up but clearly still crazy about each other, and though Callie thinks nothing is going to change, Arizona grabs her and kisses her in the elevator in a way that seems to give some hope that they might figure things out in the future, even though she doesn't say a word and just runs off afterward. And Bailey and smoking hot Dr. Warren are still dating and finally do the deed, but Bailey freaks out the next day when she sees him flirting with a nurse and thinks he's already moved on now that he's bedded. Fortunately he's able to explain himself and manages to convince her that he is still the good guy he appeared to be. She reminds him she's got a kid and a bad divorce and isn't up for something casual but he tells her solidly that he knows all that and he's not just fooling around either, and they wind up holding hands. Aw.
Party at Meredith's house! Wooooooo! Only... this time it involves people dressed up, servers with trays of tiny food and an actual bartender that isn't Mere staggering around with a bottle of tequila in her hand. She starts this week's VO: "It's a common belief that positive thinking leads to a happier, healthier life." Alex is fidgeting with his tie and they tease each other in a sickeningly cute manner -- she tells him to stop fidgeting, and then when Lexie complains that she's wearing [brand name not used because they didn't get the rights but we know she means Spanx] so that she could zip up her dress and that she's fat, Alex points out that she's got no fat on her, just a nice ass, which he happens to like. She thanks him for the disturbing yet awesome compliment and proudly juts her behind out a little more, and he asks if she wants to go make out upstairs. She refuses, though, as they are there to support Derek, and Alex just gripes how much the party blows.
Derek apparently did really redo his office, though we haven't seen it since he was cleaning out Ellis' journals. There, he's showing Mark and Owen his plans for the new house, which we also hadn't heard much about in a while. It seems the house in the woods is actually going to be built. Mere comes in and points out that at her parties they drink beer and dance on tables, and he realizes that she's insulting his party. She tells him it's getting lame but I'm sure it was lame from the start -- it's just that when people dress up and see an actual bartender they get excited for a bit and now that seems to have worn off. The guys all file out and she smiles at them, but when Owen walks past and gives her a tentative smile of her own she just gives him a smirk, much like the one that got her in trouble last week, and his face clouds right over. Her VO tells us, "As children we're told to smile and be cheerful and put on a happy face," which obviously neither of them is doing too well.
"As adults we're told to look on the bright side." Callie has her cleavage out for the party and it's rather mesmerizing, but she can only stare glumly across the room at Arizona. Mark comes over and calls her on it, then asks if she wants to go home and have sex in the shower since Teddy is stuck in surgery. She tells him, not amused, that she's not in the mood for jokes -- though I'm certain he was only half joking and would have happily jumped at the chance if she had agreed. She storms out of the room and from afar, Arizona sees this and looks bummed.