Leto knowledge that his life and reign are coming to an end, foreshadows his eventual realization that he has a real soul.
God Emperor of Dune
Leto frequently behaves in ways that seem counterproductive to the goals that a normal monarch has, for instance, allowing rebellion, inspiring troublesome fear in his subjects, etc. Even when he behaves as a monarch beliveably might, he appears to contradict how the reader would expect the protagonist and self-labeled humanist to act. He opresses his people intentionally into boredom, he promotes dogmatic and blind fanaticism, he calls himself a preadator for humanity. All of these contradictions foreshadow his plan, and the nature of the Golden Path. As the reader reads, the contradictions pile up, possibly leading the reader to potentially identify with Duncan Idaho, and view Leto as a villain, but all of the contradictions align to Leto's ultimately benevolent plan: to incite humanity to spread far and wide, to foster creativity, to teach a lesson in avoiding centralized government, and to breed a strain of humanity imune to presience and therefore any technology that could use prescience to exterminate humanity. He frequently points out that humanity will "never forget Leto's peace", foreshadoing the lesson he teaches. He talks about how he sees the future and how anyone who could see what he sees would join him.