Selim Bradley did not like it when he dreamed.
When he dreamed, he dreamed of moving shadows, of blood and death, of souls trapped for millennia, and of misery and pain. He didn't think these were his dreams; they were the dreams of someone else who looked like him and sounded like him, but wasn't him. It couldn't be him, because he had an odd marking on his forehead (he still wasn't sure why no one else had it) and the person in his dreams didn't. The person in his dreams was cruel, and loved pain; he helped others, and hated pain, and he certainly wasn't cruel (sometimes he asked himself if maybe he was only like this to be different from the person in his dreams, to separate them more so he could never be that person).
When he read the newspaper he learned about murder, and torture, and war, and every story reminded him of those dreams. He couldn't sleep for awhile after reading about those things, because he wondered if maybe he couldn't become that person in his dreams (they really were awfully similar) or if maybe he wasn't that person already, when he was sleeping and wasn't aware of himself. If he did drift asleep those nights his sleep would be fitful and he would dream of his skin falling away and him being hollow, only the shadows filling him (and the shadows were mixed with red faces, human faces).
He couldn't tell his mother any of this, and he couldn't tell Fuhrer Grumman (or later Fuhrer Mustang), because Selim had heard Fuhrer Grumman telling his mother that if he remembered "that" (and he thought he knew what "that" was) he would have to be killed. He didn't want to die, not yet at least, because the dreams were just that, dreams, so far. If they became reality he would reconsider (though maybe they had been reality once).
He wondered, sometimes, if maybe he could tell the Fullmetal Alchemist. Edward visited sometimes with Mustang, but he didn't talk to Selim much, and when he did he seemed uncomfortable, and Selim was uncomfortable with him, though he hid it behind a mask of politeness. Edward was in the dreams, always fighting the moving shadows (and he was there when the person that looked like him disintegrated along with the shadows), and Selim admired him just for that, because he knew that the shadows were wrong and should not live (but what if he was the shadows?). The shadows died, but there was always a baby left, a tiny baby, and Selim looked out of its eyes and everything seemed as large as the headquarters in Central, like he was just an ant (he didn't know if the baby had a mark on its forehead like his because he was the baby and the boy that looked like him and the shadows, in the dreams, but maybe in real life too), and Edward put the baby on his coat and gave him to his mama (who was undoubtedly his own mother).
He didn't tell Edward, though, because in the dreams the shadows and the other boy hated him, and he was sure Edward had hated them, and if he was the shadows and the boy (were they the same?) then Edward would hate him (and fight him again, and then he would die and he still didn't want to yet).
Selim didn't tell anyone about the dreams. He just watched his shadow carefully (and sometimes it almost seemed to move).