The Sisters of Silence were an ancient organization. Every member was a female Untouchable; merely standing with swords in hand, they could greatly disrupt the workings of psychic rituals.
Nominally, this organization belonged to the Adeptus Astra Telepathica, but in essence, like the Adeptus Custodes, they obeyed only The Emperor's commands. In a sense, the Sisters of Silence and the Adeptus Custodes were the two foremost military organizations beneath The Emperor himself. Regrettably, however, the Sisters of Silence never received the same reverence accorded to the Adeptus Custodes.
After the Horus Heresy ended, the Adeptus Custodes remained within the Imperial Palace. The Sisters of Silence, however, were forgotten and cast aside, forced to scatter across the corners of the Milky Way and serve The Emperor in silence. They hunted fallen sorcerers, yet were also subjected to endless suspicion and scrutiny. Unlike the Adeptus Custodes, whose bodies had been enhanced to the utmost limit, the Sisters were merely ordinary humans with a special resistance to psychic power. Faced with the Imperium of Man's many misunderstandings, they found it difficult even to protect themselves.
Some Sisters died. Others concealed their identities and lived alone in remote, sparsely populated places, or lived alongside others and bore children who possessed the same Untouchable nature.
Oedmeir had been deeply shocked when Lin Fan told her about this. For an ancient organization with such illustrious achievements to be persecuted to this extent was simply inconceivable.
If it was because the Sisters of Silence were Untouchables and could not hear The Emperor's voice, then perhaps there was some explanation for it. But the Adeptus Custodes, who had fought beside the Sisters for so long, had also chosen to turn a blind eye. That was something Oedmeir simply could not understand.
In the end, she could only blame