This. This! THIS!!!!! I needed an excuse to make this drawing. So bad.
The joke is basically that Dice is Greed incarnate incarnate. They have similar ways of thinking, but for different reasons. I'd get into them, but that would be a ton of spoilers for Survival Instincts. I'll just say that Dice was born from greed for MORE GREED. And the strange thing is that the first time I drew Dice, I didn't even use a picture of Greed as a reference.
I am loaded with Fullmetal Alchemist parody gags involving "GreeDice" in which Dice takes the role of a Greed stand-in, but having the two of them side-by-side didn't seem to fit. I was thinking of making their encounter a one-page, one-panel thing, but once Elricz brought it up, I had to include it in "Get to Know an OC".
Now let's talk about Alphonse. I was absolutely terrified of drawing his helmet. After roughing him in, the helmet wasn't so hard to do. I just needed a reference. The crazy thing is that there's this picture in the first volume of the manga that looked almost exactly like my rough sketch! The only difference was that he was using his opposite hand to point. How's that for a coincidence?
I will conclude by saying that if you don't get the joke, I forgive you. Someone I know who had never heard of my story or FMA wanted to read this page and I warned her that she wouldn't understand it at all. And guess what? She didn't.