Xur and the Speaker are brothers. A sentence made of gibberish was made into "They are vulnerable now, good. We are brothers of light one of dark. Brother, we had a fight once, but we need each other more than ever now." The speaker has said that he has a brother. So who is the one of dark? XUR. They both know the Nine. They both are always mysterious, and cryptic. Also they both never show there face(kinda). So maybe they are brothers maybe they are not. However, for some reason though. I feel that they have both Become Legend.