When they were little, Sam and Dean had cut their palms and made a blood pact. They would always be there for the other. They swore they would walk into hell for each other and out the other side. They swore they would meet whatever came their way together. They swore that come what may, they were stronger together, they would meet it together, and they would meet their ends together, never leaving the other behind.

The boys made the oaths, the men fought the war, love formed the bonds, and the blood sealed their fates.

Such was the Winchester way.