Fletcher shifted on his feet uncomfortably. "Before you get mad at your Edward, keep in mind that there could be a world difference."
That warning out of the way, he took a deep breath. "Edward starved himself in Munich so they could afford Alfons's medicines and enough food for him, and it weakened his heart from vitamin deficiency. Filia healed his other organs, but nobody knew it had gotten that bad, so nobody thought to have her heal his heart. While he was down with automail surgery, Sloth attacked and electrocuted him, which damaged his heart enough to cause scar tissue and eventual heart failure."
Then he smiled faintly. "As far as the soulbond, he and Al share a soul. When Envy killed him, and he traded himself over for Al, it ripped apart the bindings between them and it messed with both their heads pretty bad. Al was always looking for him, and Edward started doubting his own mortality, which made him a hideous patient when it came to his heart.
"But it's all okay now, because the Gate brothers that live upstairs in the first building healed the soul bond, and then the other Gate, the rest of it, gave Edward a new heart in exchange for service from the family. I'm going to enter into service when I'm old enough so my brother and I can both stay together."