From "Manual of Muad'Dib" by the Princess Irulan

I will have Stilgar send Idaho's head to this Duke , Kynes told himself.
The ducal party was only a few paces away now, their feet in desert boots crunching the sand.
Kynes bowed. "My Lord, Duke."
As he had approached the solitary figure standing near the ornithopter, Leto had studied him: tall, thin, dressed for the desert in loose robe, stillsuit, and low boots. The man's hood was thrown back, its veil hanging to one side, revealing long sandy hair, a sparse beard. The eyes were that fathomless blue-within-blue under thick brows. Remains of dark stains smudged his eye sockets.
"You're the ecologist," the Duke said.
"We prefer the old title here, my Lord," Kynes said. "Planetologist."
"As you wish," the Duke said. He glanced down at Paul. "Son, this is the Judge of the Change, the arbiter of dispute, the man set here to see that the forms are obeyed in our assumption of power over this fief." He glanced at Kynes. "And this is my son."
"My Lord," Kynes said.
"Are you a Fremen?" Paul asked.
Kynes smiled. "I am accepted in both sietch and village, young Master. But I am in His Majesty's service, the Imperial Planetologist."
Paul nodded, impressed by the man's air of strength. Halleck had pointed Kynes out to Paul from an upper window of the administration building: "The man standing there with the Fremen escort—the one moving now toward the ornithopter."
Paul had inspected Kynes briefly with binoculars, noting the prim, straight mouth, the high forehead. Halleck had spoken in Paul's ear: "Odd sort of fellow. Has a precise way of speaking—clipped off, no fuzzy edges—razor-apt."
And the Duke, behind them, had said: "Scientist type."
Now, only a few feet from the man, Paul sensed the power in Kynes, the impact of personality, as though he were blood royal, born to command.
"I understand we have you to thank for our stillsuits and these cloaks," the Duke said.
"I hope they fit well, my Lord," Kynes said. "They're of Fremen make and as near as possible the dimensions given me by your man Halleck here."
"I was concerned that you said you couldn't take us into the desert unless we wore these garments," the Duke said. "We can carry plenty of water. We don't intend to be out long and we'll have air cover—the escort you see overhead right now. It isn't likely we'd be forced down."
Kynes stared at him, seeing the water-fat flesh. He spoke coldly: "You never talk of likelihoods on Arrakis. You speak only of possibilities."
Halleck stiffened. "The Duke is to be addressed as my Lord or Sire!"
Leto gave Halleck their private handsignal to desist, said: "Our ways are new here, Gurney. We must make allowances."
"As you wish, Sire."
"We are indebted to you, Dr. Kynes," Leto said. "These suits and the consideration for our welfare will be remembered."
On impulse, Paul called to mind a quotation from the O.C. Bible, said: " 'The gift is the blessing of the river.' "
The words rang out overloud in the still air. The Fremen escort Kynes had left in the shade of the administration building leaped up from their squatting repose, muttering in open agitation. One cried out: "Lisan al-Gaib!"
Kynes whirled, gave a curt, chopping signal with a hand, waved the guard away. They fell back, grumbling among themselves, trailed away around the building.
"Most interesting," Leto said.
Kynes passed a hard glare over the Duke and Paul, said: "Most of the desert natives here are a superstitious lot. Pay no attention to them. They mean no harm." But he thought of the words of the legend: "They will greet you with Holy Words and your gifts will be a blessing ."
Leto's assessment of Kynes—based partly on Hawat's brief verbal report (guarded and full of suspicions)—suddenly crystallized: the man was Fremen. Kynes had come with a Fremen escort, which could mean simply that the Fremen were testing their new freedom to enter urban areas—but it had seemed an honor guard. And by his manner, Kynes was a proud man, accustomed to freedom, his tongue and his manner guarded only by his own suspicions. Paul's question had been direct and pertinent.
Kynes had gone native.
"Shouldn't we be going, Sire?" Halleck asked.
The Duke nodded. "I'll fly my own 'thopter. Kynes can sit up front with me to direct me. You and Paul take the rear seats."
"One moment, please," Kynes said. "With your permission, Sire, I must check the security of your suits."
The Duke started to speak, but Kynes pressed on: "I have concern for my own flesh as well as yours . . . my Lord. I'm well aware of whose throat would be slit should harm befall you two while you're in my care."
The Duke frowned, thinking: How delicate this moment! If I refuse, it may offend him. And this could be a man whose value to me is beyond measure. Yet . . . to let him inside my shield, touching my person when I know so little about him?
The thoughts flicked through his mind with decision hard on their heels. "We're in your hands," the Duke said. He stepped forward, opening his robe, saw Halleck come up on the balls of his feet, poised and alert, but remaining where he was. "And, if you'd be so kind," the Duke said, "I'd appreciate an explanation of the suit from one who lives so intimately with it."
"Certainly," Kynes said. He felt up under the robe for the shoulder seals, speaking as he examined the suit. "It's basically a micro-sandwich—a high-efficiency filter and heat-exchange system." He adjusted the shoulder seals. "The skin-contact layer's porous. Perspiration passes through it, having cooled the body . . . near-normal evaporation process. The next two layers . . . " Kynes tightened the chest fit. ". . . include heat exchange filaments and salt precipitators. Salt's reclaimed."
The Duke lifted his arms at a gesture, said: "Most interesting."
"Breathe deeply," Kynes said.
The Duke obeyed.
Kynes studied the underarm seals, adjusted one. "Motions of the body, especially breathing," he said, "and some osmotic action provide the pumping force." He loosened the chest fit slightly. "Reclaimed water circulates to catchpockets from which you draw it through this tube in the clip at your neck."
The Duke twisted his chin in and down to look at the end of the tube. "Efficient and convenient," he said. "Good engineering."
Kynes knelt, examined the leg seals. "Urine and feces are processed in the thigh pads," he said, and stood up, felt the neck fitting, lifted a sectioned flap there. "In the open desert, you wear this filter across your face, this tube in the nostrils with these plugs to insure a tight fit. Breathe in through the mouth filter, out through the nose tube. With a Fremen suit in good working order, you won't lose more than a thimbleful of moisture a day—even if you're caught in the Great Erg."
"A thimbleful a day," the Duke said.
Kynes pressed a finger against the suit's forehead pad, said: "This may rub a little. It if irritates you, please tell me. I could slit-patch it a bit tighter."
"My thanks," the Duke said. He moved his shoulders in the suit as Kynes stepped back, realizing that it did feel better now—tighter and less irritating.
Kynes turned to Paul. "Now, let's have a look at you, lad."