The Divine Predecessors are the extracted brains of former Divine Shadows, they contain all of the memories of their victims, and are a source of power and advisory for the Divine Shadow. When a Divine Shadow has reached his last moments, his body is brought to a purified human host where the kiss is performed and the essence of the Divine Predecessor is passed onto the next Divine Shadow. Once dead, the former Shadow's head is cut open, the brain is extracted and placed onto an electronic module with a clear-plastic face covering.
Many of them were devoured by a Cluster Lizard that got on board the Lexx during Lexx 1.1 "I Worship His Shadow". Others were eaten by Giggerota (who found them "too salty") in Lexx 1.2 "Super Nova", while more were harvested by Bog to make the drug called Pattern in Lexx 1.3 "Eating Pattern". The last were all destroyed by His Divine Shadow in Lexx 1.4 "Giga Shadow" when he became the Gigashadow and came aboard the Lexx to hunt down and kill the crew members.
It is later revealed in Lexx 2.13 "Twilight" that after the brains are extracted, the corpses of His Divine Shadow's earlier bodies are transported to planet Ruuma. The unique mineral deposits on Ruuma allow the bodies to live on in an undead state.
The Divine Predecessors are introduced at the beginning of Episode 1.1, they warn the new Divine Shadow of the impending prophecy, however they are placed on board the Lexx despite the ancient tradition of remaining on the Cluster. Some of the Divine Predecessors are devoured by a lone cluster lizard, and a few more are killed by Stan and Zev who used it as a way of distracting His Divine Shadow from killing Kai. One of the damaged brains, which was His Shadow who destroyed Brunnen-G and killed Kai, accidentally reminded him about his past and gave back his free will and memories.
The Divine Predecessors use their influence to call Giggerota to the gallery where the predecessors are kept and tempt her with delusions of grandeur (and ultimately Milk Fed Boys) if she complies to fetch Stanley Tweedle for them so they can escape Brunnis. After Giggerota returns with Stan's severed hand they tell her that they require Stan's entire person in order to use the Lexx and send her back down to Brunnis, however that was merely a ruse as they were able to use the severed hand while modifying their voices to sound like Stan and command the Lexx to leave Brunnis. One Divine Predecessor was eaten by Giggerota, who disliked its salty taste.
The Divine Predecessors have a much smaller role in Episode 1.3, they are merely more pattern for Bog and his slaves. The Divine Predecessors are rounded up into a sack by Bog and taken to the game room to be transformed into pattern, but are later returned to the gallery by Zev.
The Divine Predecessors humiliate Stan by recounting the time he was abducted and molested by a mercenary named Feppo and his colleague Smoor. The Divine Predecessors then begin mockingly singing about Stan's humiliating encounter.
Later Stan returns with Squish in hand to ensure a more "friendly" dialog occurs, and forces the Divine Predecessors to sing a more "stan-friendly" song.
"Stanley Tweedle is a god, a warrior, and a gent
We are not fit to suck on his feet or dine on his excrement
At night we croon by the light of the moon
Of his courage and his creed
Hey, ho, there he goes; woe, woe to his foes
Long live the Tweedle seed!
Stanley, Stanley, top of the hero class!
Stanley, Stanley, we live to kiss his ass!"
Eventually the essence of the Giga Shadow invades the Lexx while searching for Kai, Stan, and Zev, it drains all of the Divine Predecessors of remaining portions of insect's Essence (presumably of collected memories too) and exploding host brains.