Sandworms of Dune - Entry #13

     The honor and integrity of Duncan Idaho is so strong and apparent in the next scene.  Erasmus is nearly giddy over what he has done.

     "You would never have known most of them. With memory imprints, some even believed they were human.  All across what remains of your former empire, a great many people are probably quite surprised as comrades, leaders, friends, and spouses drop dead where they stand and transform into Face Dancers."  Erasmus laughed again.  "With a single thought I've eliminated our enemies.  Our common enemy.  You see, Duncan Idaho, we need not be at odds."
     Duncan shook his head, feeling oddly sickened.  "Once again, the thinking machine sees total genocide as a simple solution to a problem."
     Now Erasmus was surprised.  "Don't underestimate the Face Dancers. They were ... evil.  Yes, that is the correct word.  And since each one was fundamentally part of a hive mind, they were all evil.  They would have destroyed you, and they would have destroyed us."
     ... 

     Duncan looked at all the dead Face Dancers, realizing how much damage the shape-shifters had done for centuries, whether they were guided by the evermind or by their own schemes.  Face Dancers had killed Garimi, sabotaged the no-ship, and caused the death of Miles Teg ...
     Looking at the robot, Duncan narrowed his eyes.  "I can't say I'm terribly sorry, but there was no honor in what you -- or the Face Dancers -- did here.  I cannot agree with it.  Don't think we are indebted to you."
     "On the contrary, it is I who owe so much to you!" Erasmus could barely contain his pleasure.  "That is exactly the way I'd hoped you would react.  After thousands of years of study, I believe I finally understand honor and loyalty -- especially in you, Duncan Idaho, the very embodiment of the concept.  Even after an event that obviously helps your race, you still object to my tactics on a moral basis.  Oh, how wonderful."
     He looked down at all the Face Dancers, the astonished and confused expression on Khrone's face.  "These creatures are the exact opposite.  And my fellow machines are not loyal or honorable, either.  They merely follow instructions because they are programmed to.  You have shown me what I needed to know, Kwisatz Haderach.  I am very much in your debt."
     Duncan stepped closer, searching for some way to access the new abilities he knew lay dormant inside him.  Just knowing he was the much-anticipated Kwisatz Haderach was not enough.  "Good.  Because now I want something from you."

(Sandworms of Dune, p. 478-479)