The preservers, based out of the Sanctum, dress in gossamer-fine lavender and white garb to make their status obvious. At least one preserver was always on hand at the Conclave during its existence. They could offer only information, and could not give orders.
The memories accessible to preservers may be millennia old. It is claimed preservers have access to the memories of every dead Khalai. When a Khalai dies their memories are instantly transferred to the preservers.
The psionic link of the Khala is required to become a preserver and access the collective memory. The Dark Templar, who rejected the Khala, could not become preservers. The memories of protoss from the Aeon of Strife, who had lost their connection to the psionic link, could still be accessed. In addition, the memories of the Tal'darim of Aiur, who had cut themselves off from the Khala with the drug Sundrop, became available to the preservers upon their deaths.
Following the Aeon of Strife, the protoss discovered the xel'naga archive world of Zhakul. When the Conclave took power, all texts and artifacts from the Aeon of Strife were sealed away on Zhakul and entrusted to a trio of preservers.
Long before the Great War, the Dark Templar Ulrezaj, an alysaar scholar based on the sacred Dark Templar world of Ehlna tended to the memory crystals. He accessed forbidden knowledge which eventually drove him mad. When he was caught by other scholars, he refused to have the knowledge erased from him and fled.
In recent times Ulrezaj, now a dark archon, used his Dark Templar assassins to kill preservers. Ulrezaj considered the preservers a threat to his plans. By 2503 there were no preservers among the refugees on Shakuras.
Zamara, a preserver, was mortally wounded by one of Ulrezaj's assassins. To survive she forcibly transferred her mind from her dying body into Jake Ramsey, a terran archaeologist, using the technology of the xel'naga temple on Nemaka. This rewired Ramsey's brain and gave him both preserver abilities and a brain tumor. Ramsey's memories became available to future generations of preservers. Ramsey/Zamara found themselves being pursued by Ulrezaj, the Queen of Blades and the Terran Dominion, all of whom desired her knowledge.
Zamara was able to give her secret information to both Ramsey and Zeratul. While undergoing a ceremony at Ehlna to remove her from Ramsey's mind and place her in a pure khaydarin crystal, Ulrezaj attacked. Zamara trapped both Ulrezaj and herself in the crystal.
The Xel'naga ProphecyEdit
Zamara was not the last preserver. A trio of "immortal" preservers lived on Zhakul. However, they were captured and drained of their essence by Maar, a hybrid, who had also taken control of the Zhakul Guardians.
Zeratul delivered fragments of a xel'naga prophecy found on Ulaan to the trio of preservers on Zhakul. Maar stated "some SECRETS must remain HIDDEN" as he attempted to keep Zeratul from reaching the preservers. Maar held an advantage in that he was able to use the preservers' psionic powers to resurrect himself each time he was struck down. However, Zeratul's forces defeated Maar's servants, rescued the preservers and felled Maar one last time. The preservers interpreted the fragments and allowed the Nerazim to continue his quest.
For the preservers that appear in Wings of Liberty, it was initially intended that their models be repurposed from Tassadar. However, after it was decided to give him a unique model, the preserver models were updated as well, given shoulder and helmet variations. However, the helmets remained the same, as from a distance, they all looked identical. Their bodies use the same model as that of Zeratul and have the same animations.