It is unclear what, if anything is the "controlling" section of Terror. The only thing not shown to be replaced over the course of his appearances has been his head, which the MAX version of Terror can detach from body and affix onto another. He can use this new head as a disguise, changing his appearance and he is able to access the memory of the former owner of that brain without that victim's personality taking over Terror's. Apparently, the mystical ritual used to seal Talita's arm in a mystical armor transferred the "centre" in the arm itself: Terror has shown the ability to stay functional even if separated from it, but accelerating dramatically his rotting rate, and losing his ability to resist the personality and emotions lingering in his replaced limbs. If left with no access to Talita's arm for a longer time, he would rot to nothingness after succumbing to the personalities contained in his mismatched limbs.