Al looks at Ed and wonders when he stopped being Edward Elric and started being The Fullmetal Alchemist. When he started getting those lines around his face, that show too many stressful days fallowed be restless nights haunted by his demons. Al looks at him, Ed's eyes bleached white by the moonlight, a silver and gold angel, and wonders when this is over, if this is over, will he get his brother back, or was that part of the bargain for his body?
He looks at Ed, sitting in this barren desert and tries to remember a time when Ed's eyes shone with the fire of his convictions, when he had been well and truly alive, and realizes he can't. The Edward he knew as a child is gone and in his place is this ethereal creature, the Fullmetal Alchemist. Ed catches his eye and calls his name.
Swallowing, Al makes himself look away. That tone of voice - he's heard it before, too often. Pain, guilt, and a sorrow so deep it threatens to destroy him all hidden under a thin gilding of rage. His brother always wore them all, the mantle of the eldest sibling. Even before his mother died it was there. Sorrow for his mother, pain at being abandoned, and guilt for not taking care of their mom. Their failure only added to it. Al looks at him and swears that he will fix it. That he will fix everything.
Ed looks at Al and sees everything that he has failed in. He sees the father he failed to find, the mother he failed to protect, and the little brother he failed to save. He sees every person he has ever had to screw over or just plain screw in his quest to return what he stole from his brother. He watches the moon light glint of Al's armor and tries to remember what he looked like before and fails in that too.
But it is all right. After all what's one more mark on the list of his sins, one more wrong to fix? And he will fix them all. He will return his brother's body back to him and then he will no longer need to remember because he will see it. He doesn't think he will bring his mother back. Instead he will create something better. Something that wont pine over a fickle man and abandoned her children rather than live without him. And Hoenheim, he will find Hoenheim and he personally place twelve inches of transmuted steal between his ribs.
Edward looks at Al in this barren waste land, the reflection of moonlight on steel almost strong enough to block out his bright yellow eyes, and swears that he will fix it, regardless of the cost. Regardless of how many throats he has to slit, of how many people he has to fuck he will fix it. He swears to himself with the moon and the stars and the cold, empty desert as his witnesses that he will fix everything.