Downstairs, Chen describes Carter to Mark as "all over the map emotionally." Mark asks if she's talked to Carter about it; she says that Carter "isn't very forthcoming," and she asks Mark if Carter is "seeing anyone." Mark motions her into an empty exam room and asks Chen if by "anyone" she means a therapist, and when she nods, Mark says he doesn't know. "Well, don't you think he should?" Chen says, and Mark says he isn't a psychiatrist. Chen says she got out the DSM-IV -- only she calls it the "DMS-IV" -- and looked up Carter's symptoms, and long story short, she thinks Carter is bi-polar. Mark tells her to slow down, reminding her that Carter nearly got killed and feels partly responsible for Lucy's death: "My moods would be all over the place too." Chen wants to find out one way or the other; Mark purses his lips and looks irritated, and I don't blame him. Like, Chen? Keep reading up through "post-traumatic stress disorder." Because a five-year-old who lives under a boulder could tell you that's what Carter is suffering from.