Editing Duncan Idaho (section)

===''God Emperor of Dune''===
''[[God Emperor of Dune]]'' (1981) reintroduces Idaho as a serial ghola: Leto II has ruled as a [[sandworm (Dune)|sandworm]]-human hybrid for 3,500 years, and has continually had an Idaho ghola to serve him. Beyond his personal affection for Idaho, to Leto, Idaho represents loyalty, humanity, and the spirit of the unknown, something which the God Emperor, having perfect [[prescience (Dune)|prescience]], knows nothing of. It is also implied that Duncan is needed for Leto's plan for humanity's ultimate survival — called the [[Golden Path (Dune)|Golden Path]] — to come to fruition. However, the Idaho gholas, with their memories restored, struggle to deal with what the Atreides have become. Where before, the hallmark of Atreides rule was justice, Leto's reign has been one of godhood and oppression. Idaho's old-fashioned conscience rebels, leading the Idaho ghola to attempt to kill Leto (who as a sandworm is invulnerable to all but water and extreme violence). Leto notes that only nineteen of "his" Duncans have survived long enough to die what is considered a "natural death." In just about all of these rebellions, the Idaho ghola is killed by the God Emperor. After a certain time, the God Emperor orders another one from the Tleilaxu, or the Tleilaxu themselves just send another one as a token for their security.<ref name="God Emperor"/>

The novel chronicles the perceptions and actions of a new Duncan that has just been ordered from the Tleilaxu. Like the others before him, Duncan is appalled at what Atreides rule has become, but Leto appoints him as the head of his otherwise all-female military, the Fish Speakers. Leto also reveals that he has repeatedly used his Duncan gholas in his breeding program to genetically improve the Atreides line. The current Duncan is intended to mate with [[Siona Atreides]], the end product of Leto's breeding program: she is invisible to prescient sight. Duncan is extremely reluctant and protests, saying that he is not Leto's stud. He does catch the eye of [[Hwi Noree]], the Ixian Ambassador sent to Arrakis with the explicit purpose of wooing the Emperor. Leto forbids Duncan from having any relations with her, but he disobeys and sleeps with Hwi.<ref name="God Emperor"/>

Duncan eventually joins Siona's rebels and works with her to assassinate Leto. His plan is successful, but Hwi is killed in the process. Leto reveals that he knew of their plan, and that his death is simply another step to ensuring the Golden Path. Siona, having seen the Golden Path during her trial in the desert, realizes she was bred as a key figure for humanity's survival. At the end of the novel, she schemes on how to carefully seduce Duncan and mate with him, as Leto had originally intended. None of their descendants will be able to be tracked by prescience, forever free of any one person's vision and ensuring that humanity could never be completely found and destroyed.<ref name="God Emperor"/>

Fifteen hundred years later in ''[[Chapterhouse: Dune]]'' (1985), the Bene Gesserit [[Bellonda]] assesses the many Duncans who came before:
<blockquote>In the original and early gholas, his character had been dominated by impulsiveness. Quick to hate, quick to give loyalty. Later Idaho-gholas tempered this with cynicism but the underlying impulsiveness remained. The Tyrant had called it to action many times. Bellonda recognized a pattern. He can be goaded by pride. His long service to the Tyrant fascinated her. Not only had he been a Mentat several times but there was evidence he had been a [[Truthsayer]] in more than one incarnation.<ref name="Chapterhouse">{{cite book |last=Herbert |first=Frank |title=[[Chapterhouse: Dune]] |year=1985}}</ref></blockquote>

Although a third party work not connected to the main Dune series, but endorsed by Herbert in his lifetime, ''[[The Dune Encyclopedia]]'' provides some background on the characteristics, personalities, and often gruesome deaths of 17 additional Duncans from the time before the Duncan that is the focus of ''God Emperor of Dune'', further noting that there were "well over seventy Duncans".<ref>{{cite book |last=McNelly |first=Willis E. |author-link=Willis E. McNelly |title=The Dune Encyclopedia |date=June 1, 1984 |pages=435–455 |publisher=Berkley Books |isbn=0-425-06813-7}}</ref>