Meredith is so happy now that Derek's moved in that she quits therapy. Alex and Izzie try to persuade Meredith to let them stay, even though Derek expects them both to move out. "Remember the muffins!" Izzie says, reminding Meredith of her baking skills.
The staff is sobered when Richard announces a new set of rules for Seattle Grace: Residents are no longer allowed to specialize, playing favorites with interns is strongly discouraged, as is getting emotionally invested in patients.
George is all set to finally retake his intern exam, but a burst pipe makes that impossible. He puts his exam on hold to help the chief deal with the crisis of moving patients to the clinic. "I'm your intern for one more day, at least," he says.
The flooding gets worse and the ceiling collapses in one ER. Miranda had warned Richard to evacaute and he finally agrees, telling her, "Try not to gloat too much."
Looking for distraction from her possibly fatal cancer, a patient quizzes Meredith about her boyfriend. "Dude, you failed to mention the hair," she tells Meredith after laying eyes on Derek." "It's one of the things that make me happy," Meredith smiles.
Thanks to her photographic memory, Lexie thinks she knows why a patient's had a seven-year headache, but Cristina doesn't want to hear it, so Lexie turns to Mark. He offers to let her scrub in since she made the diagnosis, but when she passes up the chance to help George study, Mark tells her she's "pathetic."
Izzie's found a great new apartment, but her attempts to line up a roommate fizzle when both Alex and Cristina turn down the chance to share it. Meredith tells Derek that she wants Izzie and Alex to stay, "They're my family," she insists.