Welcome to Stacy's attic. How can House just travel back and forth between Stacy's house and PPTH, anyway? Doesn't she live two hours away? It could just be a temporary home near PPTH for Mark's recovery, but it looks a little too lived-in for that, and House seems to know his way around the place pretty well. Stacy points out the rat's last known location, and House starts talking about how angry Mark probably is at Stacy. "He resents you for being able to walk," House says. "Been there." Yeah, earlier this morning when you read it in Stacy's therapist's files. House says he resented Stacy for a long time. Stacy asks if his use of the past tense was intentional. House's phone rings before he can answer her and they can make a Deep Connection.

The Cottages are on the other line. Stacy leaves the room so that House can talk and because they didn't want to pay Sela Ward extra for her to stick around in this scene when they didn't have to. Via speakerphone, the Cottages report that they couldn't see anything on Kalvin's chest x-rays, due to scarring from cigarettes and whatever else Kalvin has been smoking lately, if his tox screen results are anything to go by. House whispers that they should treat Kalvin for his most recent infections. Because no one else will do it, Foreman asks House why he's whispering all of the sudden. House says he's "in the closet," hiding from Foreman's girlfriend's other boyfriend. Add Rosie the Nosy Neighbor and her spatula and you've got yourself one R. Kelly urban opera! Of course, House isn't actually doing anything with Foreman's girlfriend (since that would indicate that Foreman had a personal life), but is staring at Stacy's rat, who has come out to play. House hangs up the phone for "killin' time," and stares down his opponent as he slowly reaches for his cane, apparently having decided that it's a more effective murder weapon than blood thinners would be. Then the rat tilts his head so that it's about a ninety-degree angle from the rest of his spine and the CGI department almost pulls the effect off. House tilts his head, too, but from intrigue as opposed to a Mysterious Disease.

And it's time for a lecture from Cameron: the anti-drug. She informs Kalvin that using meth and ecstasy isn't the best thing for one's health, but Kalvin doesn't really care. He explains that he's a "PNP boy," a.k.a. Party and Play, a.k.a. Drugs and Sex. I'm only familiar with the term because I accidentally took a very wrong turn on CraigsList once. Cameron asks if the P, (a.k.a. Play, a.k.a. Sex) is safe. Kalvin says it is if his partner is negative, but no one bothers if they're both positive, which is stupid because, as Cameron says, you could get a different strain of HIV or any of the other fun diseases that are sexually transmitted. Kalvin says he doesn't want to have any regrets, because getting hepatitis is apparently something you look back on fondly, and then hacks away. He's been coughing for the last hour, although the blood in his mucus is a brand-new thing, just for Cameron's benefit! Cameron goes to put on some latex gloves, although she probably should have started with something to protect her face, because that's where Kalvin's next blood cough lands. Cameron is startled, but not enough to do something silly like move out of the line of fire, so Kalvin cough again and even more blood splatters across Cameron's face. She's still standing there when we go to commercial, apparently waiting for Kalvin just to walk up and inject some of his blood directly into an artery. I mean, honestly, Cameron, I know that fear can sometimes render us immobile, but you're a DOCTOR and should be somewhat accustomed to and well-practiced in avoiding patients' bodily fluids. When I worked in the lab, I sometimes had to handle blood that was known to be infected with HIV, and you can damn well bet I took all the safety precautions, the first one being, of course, trying to get a co-worker to do the job instead of me. I may be selfish, but I'm not stupid!