Della Carr is skating at an indoor park for a muscular dystrophy charity event as her brother Hugo watches from his wheelchair along with his friends. She then takes Hugo out on the ramps as their parents George and Claire look on. She lets him go and then collapses.
House meets Cuddy in the parking garage and is eager to make their relationship public, but Cuddy doesn't want to yet and insists that they go to HR first to register their relationship. House agrees, but makes sure to grope her first. In the lobby, Cuddy tells him that Della's heart briefly stopped and wants him to take the case, and House agrees.
The team goes into differential to review Della's case. House announces that he's seeing Cuddy, and Wilson leaves, figuring it's another practical joke. Taub warns it's not a good idea, and Foreman figures it's good they're finally together. House wonders where Thirteen is, but is curiously unconcerned when told that she's disappeared after lying to the team about a possible treatment in Rome. Chase is more interested in pursuing the case. Foreman suggests muscular dystrophy passed on genetically, but Taub and Foreman wonder why House isn't concerned about Thirteen's absence. House refuses to tell them why he doesn't care and returns to the diagnosis. House tells them to scare Della to confirm a diagnosis of long QT.
As Taub and Foreman leave, they disagree about House's testing procedure. Foreman figures that the new relationship is mellowing House out, but Taub warns that when it inevitably fails, House will be more miserable and cranky than ever.
House goes to see Wilson, who still believes that House is trying to prank him. Cuddy comes in to blame House for telling everyone, and says they need to go to Human Resources. Wilson isn't convinced since House goes to HR so often, and House tries to kiss Cuddy to confirm what's going on. She then kisses House, but Wilson isn't convinced because it's not so passionate. When Cuddy grabs House's crotch, he's convinced.
In HR, House and Cuddy try to describe their relationship to Ernest Griffin, the rip. Cuddy insists that she can supervise House and not compromise hospital business. Griffin has them sign a love contract and warns that they'll watch to see if Cuddy shows any favoritism or bias toward House. When House says how they're going to test Della, Cuddy objects and House immediately says he won't. Outside, Cuddy figures House will do it anyway and tells him there are alternatives, and he agrees. He even calls Taub and Foreman to tell them to stop the test, and she's convinced.
Della's parents want to know why they're not doing the scare test, and Taub insists that House is concerned about the patient. They send her to urinate but Della says she doesn't have to despite the amount of liquid they've given her, and they realize her kidneys are failing.
As the team goes back into differential, Taub suggests that House's relationship with Cuddy is compromising his judgment. House says that he agreed with Cuddy and that's why he changed his mind, and figures that Taub wants Heart's relationship to fail because his marriage is failing. House suggests amyloidoisis and tells them to get a bone marrow transplant from Hugo.
At the clinic, House meets with two elderly men, Sydney and his father Maurice, to diagnosis Maurice. House insists that the only thing the father is suffering from is symptoms of old age, but agrees to do the test.
Taub gets Hugo out of the room and explains the process of taking bone marrow to Della and her parents. Della refuses to accept it from her brother, and Taub reports to House. House figures that Della would have refused. As he leaves, he finds Wilson smiling at him. Wilson then wonders who is going to supervise him. When he finds out it's Cuddy, he's skeptical that it will work and notes that House wants something. He admits that he's worried about House, and House insists that he believed Cuddy was right and changed his mind.
Taub talks to Della and notes that everything she does is her living her life for Hugo. She agrees but insists it's selfless. Della starts coughing up blood and they realize it's not amyloidosis. They get her into OR, and House suggests to Cuddy that they fill part of her lung with foam. The only other alternative is suturing the lung over a period of time. Cuddy agrees with House and leaves, but House changes his mind and tells Chase to suture the lung.
House goes to see Wilson and admits he can't handle his new relationship with House. He figures that Cuddy actually disagreed with him even though she said she agreed. Wilson says that he cares enough to pull his punches, but they have to set some ground rules. House would rather avoid the problem than the issue.
The team gathers again and figures that the suturing may not last forever. Taub still thinks House is letting Cuddy compromise his judgment. Foreman suggests Goodpasture's and House orders a kidney biopsy to confirm and immune treatments to cure. As House leaves, Sydney approaches House and offers to pay him to pretend to do the tests and then tell Maurice that he can't live with Sydney anymore.
That night, Cuddy and House are in bed when Foreman calls to tell him that the kidney biopsy proved clean and her lungs are fried. She needs a new lung to live, and Taub has gone to the transplant committee. House says that they have everything under control, and Cuddy suggests that she go. House notes that he bribed her nanny to stay another hour.
Later, the team tells Della's parents that the operation was successful. However, the body is rejecting the lung, and they can't give steroids in case its infection. Alternately, they can treat for infection but she'll die of rejection. House tells them to treat for rejection, since she'll last longer. As they go, Taub notes that they proscribed a potentially lethal treatment based on a guess, and House went with the safer approach because Cuddy would eventually do it anyway. House tells Taub to get Cuddy's approval on the riskier procedure and leaves.
Maurice comes to see House and tells him to forget the tests. He insists that Sydney can't let go of him, and he doesn't want his son's help. Maurice then pays House $100 to lie on the tests and tell Sydney that he needs to be in a nursing home. House agrees and pockets the money. Cuddy storms in with Taub, having heard what House said about her ass. Cuddy agrees with Foreman, and House agrees with her and blames Taub for going against the team decision.
Taub meets with Chase and notes that Cuddy has House on a short leash, and that House isn't giving Chase any issues because he's indifferent. Taub figures that Chase isn't interested because he has a relationship of his own. Chase hints that he's 1/4th right. They get an alert on Della, whose lung is crashing, and realizing that it must be rejection.
Wilson goes to see House in the cafeteria, and House admits that he caved through an intermediary. Wilson tells him to work something out with Cuddy. Chase and Taub arrive to tell House that the infection treatment isn't working either, and House figures that it can't be LAM. As he considers the problem, Hugo comes to him and says that he wants House to do everything to save his sister. The boy insists that he's the one who is supposed to die first, and Della has never been sick up to now. House isn't impressed. However, as he goes, he gets an idea and talks to Della. She confirms that she's never had a cold, but admits she's had sore ears and congestion of the chest. Della first noticed it a year ago at a skating convention in Denver, and she ignored it because Hugo has it so much worse. House goes out and Taub follows him, and House explains she has sickle cell trait brought on by a clotting disorder. The transplant committee will never give her a second lung, but House realizes there's a way to get her a lung without the committee's approval.
Cuddy confronts House when she's learned that he plans to talk to Hugo's parents about taking a lung and bone marrow. She insists that it's coercive to tell them and Hugo isn't their patient, and refuses to compromise one life for another. House agrees, much to Cuddy's surprise. She wonders if he's deferring to her because they're seeing each, and he admits he might be. House admits that it's screwing him up and wonders why it doesn't bother her, and Cuddy admits that it is. She realized that she was wrong to okay him foaming the lung, and says that they're screwing things up. Cuddy goes to HR to have them find someone else to supervise House.
House goes to the clinic to tell Maurice and Sydney about Maurice's test results. He recommends that Maurice move into a home. Sydney renders a token protest and notes that Maurice can't feel hot and cold, and House asks to see his denture cream. It turns out that Maurice uses denture cream that he buys online, and which is giving him zinc poisoning. He then says Maurice has no reason to go into a home, and gives them both their money back while claiming it's a hospital rebate.
House goes to his office and finds George waiting for him. George realizes the transplant committee will never give Della a second lung, and wants to know what they can do. He realizes that House isn't telling him something, and demands to know what House can do. House hesitates and then says they can take marrow and half a lung from Hugo, even though it will shorten his life significantly, and won't be able to use a respirator as his condition declines. He warns George that they have until morning to decide, and George thanks him.
George and Claire argue throughout the night.
In the morning, Della asks Taub where her parents are and says she saw them arguing. She realizes her parents want a lung from Hugo, but Taub tells her she's wrong.
George and Claire realize that they can't live with their decision no matter what they choose. Taub finds Della in the stairwell. As the crash team comes to move her, Taub explains to the parents that Della realized what they were arguing about and tried to kill herself.
Later, Taub explains that Della triggered off a shock that made her condition much worse, and they only have a little more time to decide. Meanwhile, Cuddy informs House that HR couldn't find another supervisor for him. She tells him to go ahead and tell the parents their options, and House admits that he already did it. He apologizes and Cuddy admits she isn't as mad as she should be. George and Claire tell House that they're not going to take the lung and marrow from Hugo, and House blames them for letting their daughter die. Cuddy starts arguing with House about his cold attitude, and he yells right back. Hugo overhears them and goes to his sister, and tells her to put a piece of him inside her so he can be with her, and so he doesn't have to live without her.
Cuddy and House walk away, and House admits that they got lucky. He concedes that he gave he parents an impossible choice, but Hugo made it for them. Cuddy points out that their fight was the first honest interaction they've had, and recommends that they be brutally honest with each other. House responds by groping her butt and telling her she has a big ass, and they leave.