The Synicles are creatures of the Metastreumonic-force. They aren't real humans, but instead they are creatures trying to confuse their foes psychologically.
In Secreta HQ, you can hear about the story of an unknown commander's woman that somehow escaped from him and was hiding underground. The commander found her later, and he ordered for her to be tortured and have her eyes gouged out for betrayal. The story says that this has changed the commander and he was never the same as before. Like the story says, the Metastreumonic-force liked this story and created one of their own creatures on the base design of the described commanders woman.
The Research project 'Synicle corpse' says that the Synicle is able to 'modify the psychology of its victims, by something like a telepathic charm'.