Well, this is happy-ish. I guess. Good for me. I was toying with a slightly new writing style with this, so if it's weird or hard to understand or anything, sorry.
Disclaimer: I own nothing.
The last image Ed had of Roy Mustang was one he wanted to hold onto forever.
They simply clasped hands, but that simple gesture contained so much- promises to return, apologies for possible failure, and a mutual understanding that the fate of their country lay with them. But something else was there as well. The look on Mustang's face, it lit up Ed's while world in that instant. That look of pride, of love, filled Ed's soul with joy. He knew that look, instinctively. It was how his father should have looked at him. It was a look that said 'I love you, I'm proud of you, you've finally grown up, and I love you'. In that single moment, Ed realized that that was what he had wanted for years. He realized that Mustang had somehow, without either of them realizing, filled the void that Hoenheim had left, had become a father for Ed. And that thought made Ed ecstatic.
But he didn't let it show. He kept that cool, determined facade up, while inside he just wanted to give the bastard Colonel a hug, and tell him to stay safe or he'd kick his ass.
And then it was over. The two men stepped back, and Ed found his own newfound understanding reflected in Mustang's eyes. But still, masks we're kept up, right up until Ed turned around an walked away.
He didn't look back.
The last image Ed had of Roy Mustang was one he wanted to hold onto forever, because it was the last image he had of his father.