Fullmetal Alchemist: Brotherhood: an ending analysis.
So. The moment where Ed gives up his gate to Truth in order to get Al’s body is well known. Even more so, his line about being an ordinary human who can’t even save a little girl, a callback to what he said so early in the series after Nina. It’s a great contrast from the Ed who called himself the closest thing to a god, and it highlights his growth.
It’s generally accepted that the exchange was Ed’s alchemy for Al’s body. But I don’t think it was. Sure, they used their body to get information on alchemy, so the reverse makes sense. But, alchemy doesn’t always work in reverse. Especially with human transmutation. The stones can’t become humans again, and Nina can’t be separated after what her father did.
Truth asks Ed if he’s ok being an ordinary human before the transmutation. And Ed says he’s always been an ordinary human. And I think that’s what caused it to work. The brothers got into the mess by trying to play god, so they got out of it by accepting their humanity. In giving up his pride, Edward learned his lesson, as well as a fundamental truth about the world. He learned that valuing the humans who are still living is better than using them for knowledge or personal gain. I think it’s the combination of the gate and his pride that made it work in the end.