"Robin: It only happened once. Just once in the whole night that it showed. He'd given the orders and all the Mutants and the Sons and everybody is gone for a minute. And during it, I caught it. He just sagged in his saddle like an old man. I could see it for just that one moment. The weight of it all on him. The fatigue. Maybe even a smidge of doubt? Hell, fear? Then he straightened up and grinned at me, like it was a joke. He can't die...or he just won't. I don't think he ever learned how to. But why would he? A man like him? So sure and passionate about what he does? He'll live forever. That I know for sure."
January 1, 1970
https://en.wikiquote.org/wiki/Batman%3A_The_Dark_Knight_Returns