She is portrayed by Natalie Martinez and Madison Davenport.
Amaru ruled Xibalba where the celubra Nine Lords of the Night originated from, When the lords left Xibalba and went to Earth, Amaru followed and tried to hunt them down but Amaru was lead into a trap and killed by the Nine Lords and they then consumed her body. Because her blood was so powerful, it was given to one of the lords Celestino Oculto who then used it to create Santa Sangre.
In the season finale, she makes her first appearance in the series when she possesses Kate Fuller.
She sends her minions, Calavera, The Skull Keeper, and Brasa to kill the remaining Nine Lords.
She also appears at Santanico's fighting ring, she tracked down Santanico in order to kill her. While Seth is fighting in the ring, he sees a glimpse of Kate's body. She then finds Manola along with Richie. Richie tries to stop Amaru by mind controlling her. Amaru revealed to be completely immune to mind control. She then proceeded to order the Olmeca to grab Manola from the neck. Santanico approaches and demands Manola's release. Manola then stabs the Olmeca and Amaru kicks her legs and grabs Manola's face as she extracts her soul. Santanico backs down and tries to speak to Kate in attempt of save Manola. Amaru kills her completely, snaps her neck, and throws her to Santanico's arms. Amaru fled after she saw her fight and successfully defeat the Olmec. in the end, Amaru was seen enraged talking to Brasa, and tells him that she should have stayed to fight Santanico.
Amaru appears when she approaches an ancient structure made of earth. She proceeded to touch the structure and managed to create an earthquake, all the while cracking the wall she touched. All the Culebras that were stripped of their venom appear in the mountain in back of her, and kneel before Amaru.
Kate takes temporary control of her body and finds Scott. Soon after, Amaru fights her way into control again; and tries to kill Scott. Ranger Gonzales stops Amaru from extracting Scott's soul. When the jaguar warriors set a trap for Scott, Richie, and Seth, Amaru fights Scott, in her attempt to kill him. Both were seen fighting with swords and then hand to hand combat. When Amaru finally touched Scott, his special power appeared and protected him. Seth then came to Scott's rescue when Amaru took the upper hand, Amaru faked to be Kate and managed to touch Seth and begin extracting his soul. Scott then stops her and Amaru managed to flee.
Amaru along with Brasa liberate a beats that contaminates the water, and if drank it makes the person dependent to eating human flesh. She also tried to steal a mother and her child for an unknown reason, but it was stated that they were innocent and they were unaffected by Amaru's water. Amaru was stopped and fled this time as well, but brass managed to take Richie with them.
Amaru keeps Richie in the asylum where she first appear in the series. She managed to get into Richie's mind and convince him he had to kill Ximena, Ranger Gonzalez, Seth, and Sex Machine. Richie throughout Amaru's control was able to fight her. Richie was then burned by his brother Seth to break Amaru's possession.
Amaru appears at a ceremony held by a cult of celeburas who are loyal to her. There, she is captured by Seth and Tanner, who have infiltrated the ceremony, they take her to a place where her powers are warded. There, they try to exorcise her from Kate's body by tying her to a cross and stretching her body while Tanner performs a exorcism chant, which fails and she mocks Seth during this time. She escapes by manipulating Scott into freeing her. She then goes to the church where Ranger Gonzalez's family are held. There, she feels one of her demon dying and being killed. She briefly laments on her death by saying that she did not die in vain.
She puts pressure on Brasa to find the last remaining Lord, Venganza. Amaru watches as her servants pour the ashes of the Nine Lords in a coffin shaped container and then later sees Venganza again. It's revealed that in a river of blood in Xibalba Venganza would bathe her and she removes Venganza's hood while she is talking. She asks if Venganza loves her, and she tells Amaru that master and slave cannot love each other. Amaru tells her she could be given another chance, but Venganza will not have and rips out her snake, burning and killing her in the process, leaving Amaru with a saddened expression. She then starts the ritual, slicing her wrists with a short scythe and having the blood pour on the ashes while chanting, while dropping the amulet in the blood as well. Burt arrives and tells Scottto get Kate out. She appears and then faints all the blood circulates all over the coffin. Before Burt can do anything, a blood-soaked erupts and rips out Burt's heart, and it slowly crawls out of the coffin. It starts to form a figure and when she is fully regenerated, Amaru's true self is seen, telling the people in the church to bow their heads. She then begins her plan after regaining her body and fights against Santanico, cancelling out her ability in the process. She then captures and ties Richie up to use him for her plan. She then meets up with Kate again and challenges her. She shows hesitance when Kate challenges her with killing her, and she tells her that since she is a part of her, they are inseparable and that she should surrender to her. She then threatens Kate with killing her brother or anyone else, and transforms into a monstrous form. She is then impaled through stomach with a stake threw by Santanico and does battle with her. She threatens to take them all to Hell with her, and both Kate and Richie walk through the portal back Earth. Kate then pulls Amaru apart, letting the arms of the souls she ate to grab and send her back to Xibalba, with her spewing blood and screaming while being dragged back.