Whenever he slept, he had that same dream; the dream that would haunt him over, and over again. The day he lost his brother, and his two limbs; he had decided it was worth it to bring back his brother so he wasn't left alone in this world. He was the type to try and forget the past, but the past always came back to him.
Those dreams seemed so real. Well because they were, they were memories rather than dreams really. That night, they tried bringing their mother back from the dead. They wanted to see her smile once more, the smile that brought them happiness. The happiness they would get when they've fought or gotten injured. The happiness they had lost when she had left them, something they wanted back no matter the cost.
The cost was a little too much. Taking his brother's body and his own left leg, it was his fault. He didn't realize the cost would have affected both of them that greatly. In the spur of the moment of losing his brother he decided to get his brother back. He didn't want to lose both of the things in the world that made him happy. He was willing to lose anything else to get his little brother back into this world, instead of the world beyond. He had suited his own brother's soul into a suit of armor; which had taken his arm for the compensation. He was fine with that, he was happy to have his brother back even with the cost of a limb. He didn't care; he just wanted his brother back.
Both of them learned the lesson that day, that you can't bring the dead back to life. The most important lesson anyone should know. It's impossible to bring anything back to life, even if you tried and succeeded to bring anything back it wouldn't have been that person you wanted. There is only one thing to keep the dead with you, and that's remembering them with your heart.
Your heart is the only thing that could even keep the image of the person who died onto this world. Your heart makes it so that even if someone is gone and missing from that world, you remember them forever and never let their face go. Your heart is the strongest in your entire body; it keeps you alive and keeps things that matter to you together. There may be a thing called heart break, but the heart never truly breaks. The heart just wants you to forget the thing that caused you so much pain.
This boy grew up with his heart almost smashed into pieces. Losing his mother, and almost losing his brother as well. That was when he had decided to not care about himself but to care about the things that mattered to him. He wanted his brother to get his body back without any cost to his brother. He didn't care whether or not he died to save his brother, he wanted his brother to be able to eat, sleep, feel, smell, touch, and more that he couldn't do in that body of armor he now was stuck in.
He had a heart that was strong, one that tried to accept everything; a heart that could take pain and learn something from it.
A heart made full-metal.
This was Edward Elric, the boy who handled all these hardships within his heart. His heart was made full-metal.