Callie and Mark are at the bar, and she's pumping herself full of liquid courage to do... something. Mark has stayed the changed non-manwhore, and he admits to being jealous of Cristina and Owen getting married. Arizona arrives, and Callie steels herself as her girlfriend walks up. Arizona's Bubble Popping Radar is beeping like crazy, but Callie forges ahead and after some starts and stops, asks Arizona if she wants to move in. Arizona, ever graceful, asks if that's it. As she already basically lives there anyway, she's totally happy to move in, and she manages not to put her foot in it and say she thought this was going to be a way tougher question. They kiss, and despite all my annoyance, it's nice to see one of the few functional couples on this show be happy.
Mere walks in to the house and asks Hunt if he is okay, but Hunt just asks about Derek. Instead of telling him all at once what happened she gives him a wee heart attack by telling him Derek isn't coming, but after Owen hyperventilates a second about Derek having the ring, Mere whips it out and asks if he wants to choose another best man. She even offers up that Mark looks great in a suit. Oh, isn't that the truth. Hunt himself looks delicious in his wedding suit with a small pink rose pinned to his lapel. Hunt's also a little bit nervous because he knows about Cristina's last wedding, and he looks at the stairs and asks Meredith for assurance that she'll come down them tonight.
Mere goes to her bedroom and finds the bride standing on the bed in a floor-length, deep red gown with a plunging back and a long necklace hanging down in between her shoulder blades, staring at Mere and Derek's framed post-it. Cristina, it must be said, looks positively stunning, and much more herself than at her last wedding. She tells Mere that she never gave her shit about the post-it, and Meredith crawls up on the bed and just tells Cristina she looks beautiful. Awesomely, Cristina tosses back that she knows, and then asks if Owen is good. Meredith smiles, and finally comes around on the idea -- she tells Cristina that Owen is perfect. Cristina knows she means more than just "right at this moment," and thanks her. It's a sweet moment between the friends.
And that leads us into Meredith's voiceover, as Owen looks at the ring and then looks up to see his bride and her twisted sister walking down the stairs. "When we say things like 'people don't change' it drives scientists crazy." The two lovebirds smile at each other, my heart melts, and Meredith continues, "Because change is literally the only constant in all of science. Energy, matter, it's always changing." Owen positively beams as, in a perfect touch, Mere basically gives her away, placing Cristina's hand in his. Cristina gives him a little nod, and they walk into the living room where all of their friends are waiting -- at least, all of those who weren't trying to kill fellow drivers on the road earlier.