Season 6 begins with House in a mental institution for a Vicodin addiction and subsequent hallucinations. (It also begins with a great dream-like sequence of him shackled to his hospital bed set to Radiohead's "No Surprises.") Except for a two-minute phone conversation with Wilson, none of the usual characters are in the episode. Except that they sort of are.
There's the head of the hospital (Andre Braugher), who's House's confidant and intellectual match, and also challenges him, like Wilson. There's a female doctor who challenges but also enables, embodying House's former employees: Cameron, Chase and Foreman, plus a little hospital administrator Cuddy thrown in there too, minus the sexual tension. There's a married woman who's a love interest (Run Lola Run's Franka Potente), who is a lot like Sela Ward's married, former flame Stacy from seasons 1 and 2. The other inmates are the hapless patients that House normally encounters: trying to absorb wisdom from him, but generally getting rebuffed and rejected instead.