Criminal Minds, Season 1

Hotch:
Do you know how salesmen get us to buy a car? They call it reciprocity. They drop the price and it feels like they've done us a favor. We feel obligated. There's a sudden pressure to reciprocate this one little favor. And it's so powerful that we'll... put a deposit down on a car that we're not even sure we really want.

Slessman:
So what?

Hotch:
So Vogel did you a favor. He protected you in prison, and now you feel like you owe him and you need to protect him. Guys like Vogel learn in the schoolyard which kids to bully and which kids to protect, and he's got you convinced that you owe him so much that you'll go to jail for him. Richard, I'm here to remind you of something. You owe him nothing.