He understood terrible purposes. They drove against all odds. They were their own necessity. Paul felt that he had been infected with terrible purpos… - Frank Herbert

When I need to identify rebels, I look for men with principles

Leto turned a hard stare at Kynes.
And Kynes, returning the stare, found himself troubled by a fact he had observed here: This Duke was concerned more over the men than he was over the spice. He risked his own life, and that of his son to save the men. He passed off the loss of a spice crawler with a gesture. The threat to men's lives had him in a rage. A leader such as that would command fanatic loyalty. He would be difficult to defeat.
Against his own will and all previous judgements, Kynes admitted to himself: I like this Duke.

You do not beg the sun for mercy.

-Maud'dib's Travail from The Stilgar Commentary