What's dead should stay dead. That was a rule the Winchester brothers constantly defied. Death just really never took with them. It might have to do with the fact that they were so codependent that they couldn't function properly without eachother.

"Look. What's your name, kid? I'm Dean." He helped keep her steady and warm when they were finally both back on their feet. He brushed the snow off his jeans. "Who was he? Dad? Brother? Best friend?"