Alphonse Elric was bound to this world by brother's blood. He wondered if that was the reason he had such a keen awareness of his brother, even when they were not in view of each other.
It was the only thing that made sense; reason told him such an almost telepathic link was impossible.
"Hey," Edward said beside him in the train seat. "Don't act like you're asleep. I can feel you breathing."
Alphonse looked at his brother and smiled at him, an act physically impossible for the suit of armor.
It was just the way they were, Alphonse decided.