The rest of the Brotherhood of Sateer , and Sateer himself are trapped in a pocket universe, learned to communicate transspatial with the Five of the Brotherhood that managed to remain outside the pocket universe and survive the cataclysm of the collapse of the previous Universe.
Individuals like the First Son of Darkness  who spend much effort and much time in researching the "mythical legends" and the "dark arts" in turn foudn ways to communicate with the Brotherhood.
Now communication is not always possible, and the level of understanding in terms of language and comprehention is not always ideal. Leading to the legends and prophecies that exist.
It is suspected that the Shadow of the Brothehood is the true source of "the Prophecy of Before and Yet to come "
Since they are unable to interact and only appear to individfuals who know how and when to contact them. Their influence is shadowy at best and hence the name.
(The Dark One crushed the Pocket Universe and this terminating the Brotherhood forever in 5101)#
 See Larthop