The phrase "deal with the devil" is a phrase used to describe making a bad agreement or decision, usually with someone you don't trust. It means that if you make this bad deal, something bad will happen and you won't get what you want. The phrase often comes up in stories, where the main character makes a pact with an evil character for power, money, or to get something they want. If the character agrees to the deal, the devil takes something from them in return, like their soul or their freedom. Making a deal with the devil is a bad idea, because even if you get what you want, it usually comes with some kind of consequences that are worse in the end.