Season 1 Lady Demerzel serves as a trusted aide and advisor to the elder Cleons, Brother Day and Brother Dusk, and as teacher and governess to the young Brother Dawn. Demerzel is shown to be a devout Luminist in "
Death and the Maiden", and goes so far as to kneel before the upstart Zephyr, Halima Ifa, who has spoken out against Imperial cloning on religious grounds. In "
Mysteries and Martyrs", Day is furious at Demerzel for committing this heresy, but she counters that if her action was truly in opposition to the Empire, her programming would not have allowed her to physically do it. She appears to suffer a crisis of faith, her conscience in conflict with her duty. Faced with the reality that her true loyalty is to the millennia-spanning bloodline and not the Cleons themselves, Demerzel screams in frustration in her chambers, tearing the skin from her mechanical skull. At her own suggestion but on behalf of Empire, Demerzel visits
Bel Riose, a former general imprisoned for disobeying the Emperor, in "
King and Commoner". She recruits him to investigate the Foundation, which the Empire has recently learned was not destroyed as previously thought. Sareth and her advisor
Rue Corintha discover Demerzel's robotic nature in "
The Sighted and the Seen". In "
A Necessary Death", a petulant Sareth's suspicions are confirmed when Demerzel insinuates that she was somehow involved in orchestrating the murders of Sareth's entire family. In "
The Last Empress", Day decides to deal with Hari Seldon's troublesome Foundation on the planet
Terminus in person, despite the protestations of Dusk and Demerzel. Dusk, prodded by his ex-lover Corintha, realizes that he has somehow been programmed not to question Demerzel's role or origins. As Dusk and Corintha discover a secret chamber guarded by a projection of Cleon I, Dawn and Sareth also realize that Demerzel has been controlling the Empire all along. In "
Long Ago, Not Far Away", Dusk and Corintha learn Demerzel's backstory, and her function as the true guardian of the Empire, after which Cleon I traps them in the chamber. On Terminus, Day confronts Seldon's avatar, who ignores him and instead speaks to Demerzel. Seldon understands her true role, and once he is assured she understands his mission, he gifts her with his Prime Radiant and its psychohistorical equations so that she may use it to guarantee humanity's survival. Day believes he is different than all the Cleons before him, and orders Terminus to be destroyed. Demerzel laments her failures in raising him, and abruptly leaves him on the Imperial flagship and heads back to the capital planet,
Trantor. She cries as she watches Terminus burn. Demerzel confronts the trapped Dusk and Corintha in the season two finale "
Creation Myths". Dusk marks Demerzel's neck with green paint before Demerzel kills him and Corintha. Demerzel has feigned acceptance of Day's plan to end the Genetic Dynasty, but orchestrated the attempted assassination to be rid of Sareth by blaming it on her. Dawn recognizes the green mark as the sign of a traitor and flees Trantor with Sareth, who is pregnant with his child. Day is killed by
Bel Riose. Demerzel decants three new Cleon clones, and activates the Prime Radiant.
Season 3 Over a century and a half later, Demerzel's use of the Prime Radiant assists the Galactic Empire in preventing their decline, allowing them to hold onto power longer than Seldon had predicted. By this time, the increasing instability of the Cleon clones has forced Demerzel to shorten the clock on their rule. Demerzel has begun unburdening herself to Zephyr Vorellis who has her memories wiped at the end of each session, revealing the history of the Robot Wars and the Zeroth Law. Demerzel also confesses to having been beyond the bombing of the Star Bridge and Trantor Station in season 1 to indirectly establish the Foundation and extend the reign of the Empire and the genetic dynasty. Demerzel has been living in a paradox ever since she received the Prime Radiant as the end of the Galactic Empire was inevitable and once she outlives her programming, Demerzel has no idea what she'll be. Following the fall of Kalgan to the Mule, Demerzel reveals to the current Dusk, Day and Dawn that her consultations with the Radiant showed that events were in motion that predicted the end of the Empire in four months despite their efforts to arrest the decline. Not only that, but the darkness beyond could also represent the extinction of the human species. After discovering that Day's lover Song is a member of the Inheritance, a cult that worships Demerzel's kind, she erases Song's memories and sends her home, angering Day. After the destruction of Kalgan and the apparent death of Dawn, Demerzel finally meets Gaal Dornick who shows the robot her visions of the future. Demerzel outwardly dismisses them, but later consults with Kalle in the Prime Radiant, revealing that she had recognized the location as a hidden area of the Imperial Library where the last robot survivors had hidden out at the end of the Robot Wars. Demerzel considers leading the Second Foundation to it for safety, but is again conflicted on the matter. On the day of Dusk's ascension to Brother Darkness, Day reveals to Demerzel that his investigation into the Inheritance has led Day to uncover the Brazen Head, the head of another of Demerzel's kind who Day has briefly seen activate. By linking with the head Demerzel, who had believed herself to be the last of her kind, can free herself of Cleon's programming. Although hesitant to free herself, Demerzel talks Day through activating the head to see if the robot is still alive. At the same time, Darkness launches a coup, destroying all of the Cleon exponents and moving to seize power for himself alone, believing this to be the culmination of Demerzel's prediction about the end of the dynasty. Demerzel gives Foundation ambassador Quent directions on how to find where Demerzel has helped the Second Foundation hide before confronting Darkness. Taking advantage of Demerzel's programming to protect the bloodline, Darkness lays a baby Brother Dawn in the vaporization machine and activates it, forcing Demerzel to enter the beam in an attempt to protect the baby. Demerzel's efforts fail, resulting in the death of Dawn and her own destruction, leaving behind the Prime Radiant to be claimed by Darkness. However, Day and Demerzel's efforts to reactivate the Brazen Head succeed, resulting in it sending a signal to Kalle and other robots based on Earth's Moon. == Literary origins ==