The chi flows in its circuits through the body, just as blood pulses through the veins. The Ishbalans call it ama, God's breath within you. But they don't know that it's the same thing.
The warrior priests are taught to call ama within themselves, to rise up through pain and seek out their reasoning mind beyond it. The discipline takes a long time to learn. He had seen his brother run on a broken leg, seen him fight when he should be doubled over with agony. He was always curious to learn that discipline, to search through it and come to understand how it worked. Now, he wished he had. But there hadn't been time.
He sat on the dusty ground by his brother's side, and watched his brother's life pulse out of the wet ruin of his shoulder, into the earth. He couldn't rise. In his own side, there was a smashed hollow as wide as a man's fist. A moment ago, it had held a jagged piece of shrapnel. The moment before that it had held the organs that sustained his life, a system neat and whole, circulating energy. Wrecked in a second, by a single, ignorant idiot who thought that the purpose of alchemy was to rain destruction upon the world.
Three thoughts resonated in his mind, again and again: the pain, the alchemy and his brother. His brother was dying — but his discoveries could save him, and his brother in turn could save his discoveries — but the pain pushed the formulae back into the depths of his mind. To find the formulae he needed to climb through the pain. His brother, who knew the flow of chi within his own body but didn't know that he knew it, his brother who could run and fight on a broken leg, could have done this. He himself could not.
His little brother had always been stronger and faster than he was. When they had been young, they would sometimes hunt rabbits together, with a net. He had been terrible at it, of course, but his brother had been skilled. He remembered how fast the creature moves, how you must hold yourself completely still, until you have it — then quick as you can, jerk the net closed.
Perhaps, just as his brother had learnt chi but did not know it, he himself had learnt something without realising it.
He held himself still. For a heartbeat, two, three. A pang of animal fear formed; he let it float to the surface and harmlessly pop. Again. One, two, three. And now, in a clear, perfect circle, the formula floated in his mind.
The moment he had it, he moved.
And as soon as he had thought the thing, it was done. Everything else he needed was written upon his skin — and then, in the work of a moment, it was written upon his brother's. His brother's blood pulsed under the lines and circles that contained everything he had learnt. His brother's chi flowed again in a clean circuit.
He would have liked a little more time, to consider his own death. More than that, the new knowledge on his brother's body would be so difficult to bear for him. He disapproved of this work; it was an long, fruitful argument between them, about their different understandings of the world, one which they would now never have time to finish. His brother understood the breath of God, but he did not yet understand that alchemy flowed through creation the way God flowed through it, the way ama flowed through the body and soul. He only wished that they could have had the time to reason together about this decision he had made for both of them. Even just a moment to try and explain, to hand him this burden properly, to ask for a promise. But his brother, with his love of justice, of family, of ama, God within people: he was a promise in himself.
Now he lay in the dust by his brother's side, and his life rapidly pulsed out of him and into the earth. Next to him, he saw his brother breathing evenly and deeply, strong and whole again, ready to take his gifts to the world.
They were brothers. It was as good as a promise.