Ed should have remembered this from that month on the island, back when he was a kid: you can only be in the great outdoors so long before you start dreaming of hot showers. And of dumping the people you're travelling with in them.
Stay observant! Amestris needs you!
Hadn't he survived a month on a deserted island when he was ten, equipped only with a little knife and one pair of shorts? He was tough. He was rugged. He could fall asleep anywhere. He could totally do this.
Tomorrow: having to talk to fucking Hohenheim. The day after tomorrow: the apocalypse. No pressure, eh?
Ed tilted his head down, looked up under Greed's bangs — and there, he saw a familiar, shaky grin.