Wilson says House has no right to do this. House says if they're not friends anymore, then he has the right to do whatever he wants. There's no trust between them to breach. House can tell everyone Wilson's secrets and have him followed. Oh my god, House is such a child. A child! I think I pulled something like this (in terms of telling an ex-friend's secrets, not the PI part. But only because my allowance wouldn't cover that) when I was eight. With that, House starts talking about his patient again like nothing happened. Wilson says he has rights, too. He has the right to walk away from House and live in the wide world that exists beyond House. And House should realize that world exists, too. "The next time you knock, I'm not answering," Wilson says. "Nothing yet. Keep talking," House says. This is definitely the way to rescue a faltering friendship. And by that I mean getting "the door slammed in your face."
A defeated but not ready to admit it House limps down the sidewalk past the PI. "I'm sorry," he says, having listened to the conversation that just transpired. House asks the PI how many friends he has. "Seventeen!" the PI answers immediately. He doesn't really have seventeen friends; he just pulled out a number because he knew House was only asking the PI the question to refer back to himself. "I have one," House says; "had one." What about Cuddy? Why aren't they friends? The PI says friends are important, and House asks if he's charging him for this. The PI says he is if they aren't friends, but when House asks if they can be friends (because he's cheap) the PI declines, saying House scares him. House doesn't understand why Wilson has to be his friend for them to talk. At this, the PI says something that makes no sense but gives House the epiphany he needs: "friends are friends. Customers are customers. And everything else is everything else. If it's not, nothing is nothing."