Prothean

The Protheans were an ancient race that mysteriously vanished more than fifty thousand years before the modern era. Arising on a single world, they built an immense galaxy-wide empire encompassing many spacefaring species. For ages they were credited with creating the Citadel and the mass relays, feats of engineering whose core technology underpinned all contemporary civilization, and their surviving artifacts were of immense scientific value. In truth the Protheans had inherited rather than built those works, and were themselves harvested by the Reapers, the same cyclical extinction they had been powerless to prevent.

Biology#

The Protheans were an anthropoidal race with two pairs of eyes, each eye possessing dual pupils, and three pairs of nostrils; like the turians their voices carried a flanging effect. Their heads were covered by a thick, layered carapace, and their skin was a pale blue-grey or brown mottled with muted yellow spots. A unique attribute of their physiology was an experiential exchange system based on physical touch: by touching something or someone, a Prothean could recall its experiences, learning a new skill or language with a single contact. This sense had arisen because the Protheans had evolved as hunters who needed total awareness of their environment. At least some Protheans wielded potent biotic abilities, and their genetic material revealed a distinctive "quad-strand" DNA structure.

Forging an empire#

Little is known of the Protheans' origins; even the name and location of their homeworld were lost to history, though one of their communication devices was dated to as early as 68,000 BCE. After achieving spaceflight they discovered the ruins of an earlier spacefaring race, the inusannon, and from them learned mass effect physics and developed faster-than-light travel, an advantage they kept secret for centuries. They expanded across the galaxy by way of the mass relay network and made the Citadel their capital.

Early in their development the Protheans encountered a hostile machine intelligence that threatened to overwhelm them. To defeat it they resolved to unite all of the galaxy's organic life under their empire; races that resisted were crushed and assimilated, until each came to think of itself as Prothean. United under a single cause, the empire held off the machines in a conflict known as the Metacon War. During this age the Protheans observed and cultivated promising primitive species, among them the asari, the hanar, humans, the quarians, the salarians, and the turians, planting outposts near their homeworlds and intending one day to offer them the "choice" of joining the empire.

The Reaper harvest#

The Protheans' confidence that they could match any machine intelligence was shattered when the Reapers arrived around 48,000 BCE. The Reapers entered through the Citadel, instantly decapitating the Prothean government and disrupting the relay network, isolating Prothean systems from one another, while records on the Citadel handed them the census data and star charts needed to track every Prothean in the galaxy. The empire's greatest strength, its unified structure under a single ruling species, became its undoing, for once the leadership was compromised its scattered forces could not adapt.

Over the following centuries the Protheans fought the Reapers from system to system, sacrificing whole colonies to buy time even as the strategy steadily drained them. They were also betrayed from within by indoctrinated Protheans who served as the Reapers' sleeper agents. Learning of the cycles of galactic destruction from the ruins of earlier civilizations, they discovered plans for the Crucible and set about building one, but indoctrination claimed even those who hoped to control the Reapers, and the project was sabotaged. In time the Reapers had killed or enslaved every Prothean, stripped their worlds, and retreated through the Citadel into dark space.

The survivors#

A few Protheans escaped the immediate harvest. On Ilos, a research team survived in cryogenic stasis under the watch of a virtual intelligence named Vigil, which cut power to non-essential pods over the centuries to preserve the most vital researchers. When the Reapers withdrew, the surviving scientists chose not to attempt to rebuild but to protect the younger races the Reapers had spared. Using the Conduit, a miniature prototype mass relay, they traveled to the Citadel and altered the signal that compelled the keepers to open the relay to dark space, intending to trap the Reapers there. Their fate was unknown, though Vigil surmised they eventually starved on the Citadel. Generations later this work bore fruit when Commander Shepard found Ilos and Vigil's data helped foil the Reaper Sovereign's attempt to summon the rest of its kind.

Elsewhere, nearly a million Prothean warriors and their commander, Javik, were stored in stasis on Eden Prime, meant to rebuild the empire once the threat had passed. Indoctrinated traitors leaked the bunker's existence, and most of the pods were destroyed; the facility's virtual intelligence diverted power to keep Javik's pod alive in the hope that a future civilization would revive him. More than fifty thousand years later Shepard could discover and awaken him, the last known living Prothean, who took vengeance as his remaining purpose.

The Collectors#

Not all captured Protheans were simply killed. The Reapers attempted to render the genetic material of millions of Protheans into a new Reaper, and when that failed they repurposed the captives, indoctrinating them, augmenting them with cybernetics, and across cloned generations genetically rewriting them into an entirely new race. Fifty thousand years later this race was known to the galaxy as the Collectors, a rarely seen people who dwelt in a base beyond the Omega 4 Relay. The link between the Collectors and the Protheans went undiscovered for ages, until the Reaper Harbinger directed the Collectors to abduct human colonists as part of a renewed extinction effort and Shepard struck at their base.

Legacy#

Though the Protheans had not built the Citadel or the relays, they were scientifically formidable, raising vast cities and arcologies, building a galaxy-wide communications network of mind-to-mind beacons, and creating data stores that still functioned after fifty millennia. Their greatest achievement was the Conduit, a working miniature relay. Their deepest influence, however, lay in their study of younger races. A small data cache in a ruined Prothean station on Mars introduced humanity to element zero and the Charon Relay, advancing the species by centuries. The hanar, who called the Protheans the "Enkindlers," credited them with the gift of sentience and language. Most profound of all was their effect on the asari, whose development, biotic aptitude, and very goddesses traced back to hidden Prothean intervention, for Javik claimed his people had cultivated the asari as a failsafe to succeed where the Protheans had failed.