Sentient

Sentients are biomechanical robots created by the Orokin for the purpose of colonising the Tau Ceti system on their behalf. During their time there, the Sentients developed sapience and rebelled against their creators.

Overview
Having established their empire throughout the Origin System, the Orokin sought to expand their rule to the Tau Ceti system. Despite the misgivings of the Orokin executors, the Sentients were created to colonise the system and pave the way for the Orokin. They were designed to rapidly adapt to anything that may harm them, gradually developing a rapid resistance to any source of damage. Put simply, firing a gun at a Sentient would cause each subsequent bullet to inflict less and less damage. To avoid the risk of the Sentients turning on them, the Orokin also impaired them with a weakness to the Void, impairing their replication and adaptation capabilities. The intention behind this vulnerability was to nullify the threat of a Sentient uprising by leaving them stranded in Tau Ceti.

While in the Tau Ceti system, the Sentients developed sapience and claimed the system for themselves. Remembering how the Orokin had effectively destroyed the worlds of the Origin System through their rampant imperialism, the Sentients decided that their new home would suffer the same fate. To prevent this, they returned to the Origin System, travelling through the Void and effectively sterilising themselves in the process. Throughout this conflict, the Old War, the Sentients demonstrated their ability to take control of Orokin technology and turn it to their side. Desperate, the Orokin unleashed the Tenno against the Sentients, turning the tide of the war.

Eventually, the Orokin were betrayed by one of their own. Ballas, executor of the Orokin, had become vengeful after the execution of his lover Margulis, and so had supplied the Sentients with information about the Tenno, revealing their origins and the source of their power. A Sentient called Natah was sent to the reservoir and assumed Margulis' form, taking command of the Tenno. However, Natah had become sympathetic of the Tenno, discovering their true nature as Void-altered children. This, combined with Natah's inability to replicate and her desire for a family, led her to consider the Tenno her own children and help them fight against her fellow Sentients. Once the Sentients were defeated, Natah, now known as the Lotus, directed the Tenno to turn against the Orokin, destroying the empire from within.

Since the Old War, the Lotus continued to serve as guide and mentor to the Tenno. However, with the Grineer's discovery of her father's remains on the ocean floor of Neptune, the Sentients had since started their gradual return to the Origin System. With their return, the Corpus had since begun extensive research into reverse engineering their technology, creating robots and even cyborgs based on the Sentients, which they referred to as Amalgams.