Dean and Death are the presidents of fast food fanclub
Of course Dean and Death are fans of fast food. It’s a more efficient killer than both of them put together.
So I have this wild theory that they have such similar tastes because Death actually *is* Dean, but existing outside of linear time (like, at some point later on in the timeline we’re seeing, Dean becomes Death and transcends linear time).
And this is also why Cas can’t seem to stay dead, because Death/Dean won’t reap him (not because, as Cas assumes, God keeps resurrecting him).
How freaky an end would that be?