A legendary Swordmaster and virtuoso warrior, Duncan Idaho may be House Atreides’ deadliest weapon. A fearless pilot and expert in stealth reconnaissance, he is the eyes and ears of Duke Leto, and the first of House Atreides to leave footprints on the desert sands of Dune. A man of loyalty and lethality, his guiding principle is to fight for the royal family as though they were his own, and to defend Paul Atreides with his life.
Idaho served under Leto during his reign on Caladan and further on his reign on Arrakis. Duncan is one of the only survivors during the attack on Arrakeen by the Harkonnens, particularly due to his fighting ability, but because of his reputation as a master swordsman, soldiers seemed fearful of him and let him steal an ornithopter and fly to safety.
Idaho teams up with Liet-Kynes following this and welcomes Jessica and Paul to the research facility. He seems saddened to hear of the death of Leto but welcomes Paul as the new Duke of House Atreides and therefore, head of the house. Duncan plans to escape Arrakis and get both Jessica and Paul back to safety on Caladan, but find he is unable to resist fighting with a hoard of Sardaukar troops when they attack the facility. Despite his bravery, Idaho falls at the hands of the troops.
Differences from the original character
Duncan is fairly similar to his book counterpart, although the latter's personality is largelly only hinted at in the original novel. Both versions of the character feel very duty-bound to the Atreides, considering them not only higher-ups, but a surrogate family of sorts. The main difference lies in Duncan's expressiveness. In the novel, Duncan tries to portray himself as more stoic and reserved, even though he has the occassional faux pas when he drops his guard and is less overly self-conscious (e.g. the one time he becomes drunk with spice ale). In the film, Duncan has a much more open and easy-going personality, and often shows dry humour or enthusiasm. At the same time, he often tries to stay calm and concentrated while under pressure, similarly to his novel counterpart. As in the novel, Duncan is also portrayed as younger than Gurney.
In the film, Paul has a similar deep-seated admiration for Duncan as in the novel. Due to Paul's lonely aristocratic upbringing and having virtually no friends of his age, Paul looks up to Duncan as something of an unofficial older brother. This angle is even emphasized in the film compared to the novel. Early in the film, Paul admits to Idaho he dreamt a vision of him falling in battle on Arrakis. Idaho's death eventually comes to pass while he's slowing down the sardaukar to aid Paul's, Jessica's and Dr. Kynes' escape. His death leaves Paul devastated, even though he has little time to mourn another dead or lost member of the family.
Both the book and film Duncan serve in an advance team sent to Arrakis to contact the Fremen and offer them an alliance with the Atreides, and both of them equally express admiration for the Fremen, their resourcefulness and fighting skills.
Compared to previous screen adaptations, where Duncan's famous swordfighting prowess was little depicted, it is highly emphasized in Villeneuve's adaptation. Though Idaho's training by the Swordmasters of Ginaz is not brought up explicitly, he is repeatedly shown going toe-to-toe with several of the emperor's highly-trained sardaukar. As Duncan states, "When you cross swords with a Sardaukar, you know it.". Similarly to the Duncan of the novel, he's also depicted as a skilled pilot of ornithopters, and even other types of aircraft.
The casting of Jason Momoa, who is of Pacific Islander ancestry, is the first time a live-action depiction of Idaho portrayed the character as one of a non-European/non-Euro-American phenotype. This is true to the source material, as in the novels, Duncan's somewhat darker skintone is noted a few times. In one of the later novels, Frank Herbert also mentions the epicanthic folds of Idaho's eyes (implying some East Asian elements in his appearance), emphasizing his complex ancestry. Based on Herbert's descriptions, John Schoenherr's illustrations for a 1970s edition of Dune depicted Duncan with a darker skintone, more akin to that of a Native American or Polynesian. 
|Characters from Dune (2021)|