The mirror universe counterpart of Saru, a nameless Kelpien slave who attends Captain Burnham aboard the ISS Shenzhou and is later spared and befriended by Emperor Georgiou.
The mirror Saru first appears in The Wolf Inside as a silent servant who bathes and dresses the captain. Burnham is sickened to learn that Kelpiens are slaves and food here and that he has no name of his own. He later saves her life when Tyler attacks her.
He returns in the two parts of Terra Firma. Georgiou, reliving her past with the conscience she has acquired in the prime universe, takes him as her personal attendant and tells him what his people do not know: that the vahar'ai is a change to be survived, not a death sentence.
Having passed through it, he fights at her side in the final struggle with Burnham. Her kindness to him is part of the evidence the Guardian of Forever weighs in her favour.