Probably because I was too shocked at what happened immediately after to think at first. And for some reason I assume that the rest of you already know this, but I'm sharing it anyway.
"Then he abandoned me. You must understand, right? Why I hate him..."
Envy hates Hohenheim for abandoning him -- a lot.
Guess who else felt the same? Ed! Ironic, isn't it?
Furthermore, most of their passion and motivation comes from that fact. Though it seems Ed has matured a lot in his travels and moved on, but at least in the beggining it seemed most of his energy came from the hatred of his father (Probably because that directly caused Trisha to get depressed, causing her to grow ill and die, causing Ed and Al to try human transmutation and lose their limbs in the first place, causing everything that followed...)...but yeah, Envy similarly seems to be very passionate about anything relating to Hohenheim, and is mostly motivated by his hatred towards him.
So really, Ed and Envy aren't too different -- they're practically the same!...minus the whole hating humanity and loving to watch people suffer thing.
Therefore I declare that irony is good, and that this calls for some hawt Ed x Envy action. Yep >_>;