Usually installed at the base of the skull or along the spinal cord, a Cerebral Grepper looks vaguely caterpillar-like, with it's front end burrowing into the victim's flesh.
An Abomination] with an installed and functioning Cerebral Grepper is normally enthusiastically loyal and must obey both the spirit and the letter of any instruction given by people the 'grepper recognizes as in authority. But it becomes possible, as the creature masters arcanowave, to overcome this compulsion by making Powers or Willpower checks against the Medicine Action Value of the controlling technician when the Cerebral Grepper forces the character to act against his convictions. The Cerebral Grepper punishes such disobedience, so the character takes WoundPoints equal to the Outcome of the check, whether it's positive or negative. For each point of negative outcome, the character is unable to resist again for one Sequence. For each point of positive outcome, the character can be the devil's advocate, obeying the letter but not the spirit of any instructions, for one sequence. If you manage a positive outcome equal to the installer's Medicine, the Cerebral Grepper burns itself out, but still inflicts damage.
It takes a Medicine, Arcanowave device or Sorcery (using Exorcism or Restore Chi) action result of 25 to remove a Cerebral Grepper without causing injury. Any negative outcome counts as a failed DeathTest, but still destroys the 'grepper.
Slave Chip
The Tharkoldu of TORG have invented a variant of the Cerebral Grepper, called the Slave Chip, that works on humans but not on demons. It uses Powers rather than Medicine but is otherwise the same.