House, Season 3

Dr. House:
[explaining why he became a doctor] When I was 14, my father was stationed in Japan. I went rock climbing with this kid from school. He fell and got injured, and I had to bring him to the hospital. We came in through the wrong entrance, and passed this guy in the hall. He was a janitor. My friend came down with an infection, and the doctors didn't know what to do. So they brought in the janitor. He was a doctor. And a Buraku - one of Japan's untouchables. His ancestors had been slaughterers, gravediggers. And this guy he knew that he wasn't accepted by the staff, didn't even try. He didn't dress well. He didn't pretend to be one of them. People around that place didn't think he had anything they wanted, except when they needed him - because he was right, which meant that nothing else mattered. And they had to listen to him.