Salt, iron, silver, and holy water; God is great, beer is good, and people are crazy; death and taxes; everything ends bloody, everyone dies alone. These things are inevitable. But Sam and Dean are old hands at dodging death and taxes (and 'God is great' isn't holding up so well either; neither are salt and holy water, come to that, because Azazel ignored the salt lines in Stanford and the holy water in Jefferson City), and also they are stubborn contrary fuckers who don't handle loneliness real well, so when they hear Gabriel say "it's gonna end bloody for all of us—that's just how it's gotta be", all it does is stiffen their resolve.