3.65 - Dune: Messiah ends with the birth of Paul's children Leto II & Ghanima. At the end of Messiah Paul loses his ability to see and since Paul follows the Fremen way of life, he is sent to the desert. The book ends as Paul walks off to his unknown fate, and Alia ultimately becomes a mother figure to her niece and nephew.
In Children of Dune we heavily follow Alia and Leto II as they narrate. Alia ultimately loses herself to the spice and her grandfather Baron corrupts her mind from the afterlife, which causes Jessica to return to Dune.
The events that happen in Children of Dune leave us with Leto II accepting the worm suit and deciding to give himself up to the worms of Dune, preserving him and Dune. This leads us into the future by 1,500 years... Due to Leto II adopting the worms suit and years later he has become a tyrant.
Both Children of Dune and God Emperor of Dune are fantastic books but for different reasons. Children of Dune is fantastic because it showcases the affects of childhood and the ways responsibility and power corrupts people. This then leads us into God Emperor of Dune which does an amazing job dissecting religion, and our historical (in)accuracies through Leto II having existed for years and creating the society he deems "correct"
These books are still very topical and accurate today, especially with how Frank Herbert views religion and politics. It honestly feels like reading real life at points, especially in God Emperor, with how Leto talks. Amazing dissections.