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"House"-hold name: Michelle Trachtenberg as Melinda.
"House"-lights: Melinda is a girl who underwent a heart transplant after her chest was crushed in a car accident. Thus, with a compromised immune system she has to be kept in a constantly clean environment. It turns out she's been secretly having relations with her boyfriend Dan and her anaphylaxis is caused by a tick in her nether regions.
Out-"House": Michelle Trachtenberg first burst on the scene as Buffy's younger sister Dawn on "Buffy the Vampire Slayer," but has since been terrorizing the Upper East Side on "Gossip Girl."