Ed did not want to die without seeing Alphonse again.
Before this war, he'd never wiped human blood off his automail.
"...If I...really went insane...I mean, completely lost my mind..." Ed said, carefully, "do you think you'd be able to stop me?"
Screaming or crying would have been appropriate. Edward Elric didn't care about propriety. He was laughing.
Mustang fell into a kind of trance whenever he killed with his flames -- snapping his fingers continually, sometimes so fast that both his hands blurred.
"Listen, bastard... Do you always have to do things the hard way? You never, ever make it easy for me."