Upbringing and Inheritance
Liet-Kynes inherited his father's mantle and served as both the planetary ecologist of Dune and leader of the Fremen. He continued his father's vision of gradually terraforming the planet from a harsh desert world into a temperate world with precipitation, greenery, and open water.
Involvement with House Atreides
Upon the arrival of House Atreides on Arrakis, Kynes acted as arbiter of succession in regard to the change of fief, as ordered by the Padishah Emperor Shaddam IV. Kynes' role was to report to the Landsraad and the the Emperor regarding the legality of the processes used by the Atreides in taking control of the planet, after House Harkonnen was ordered to leave.
Through his intelligence network, Duke Leto Atreides quickly came to realise that, as well as maintaining official imperial duties, Kynes also possessed some authority with the Fremen. Reports indicated that Kynes had "gone native". As a result, Duke Leto attempted to show Kynes as much as possible that he was taking control of the planet in an honourable fashion. Moreover, Leto realised that if he could get Kynes on side, it could possibly go a long way in winning the Fremen over, who had long-standing suspicion and distrust for the Faufreluches due to their lack of concern for the welfare of the native inhabitants of Arrakis.
Loyalty and Death
Kynes' act of saving the Atreides served to illustrate a point: the Atreides, through their honourable ways, could instill fanatic loyalty in people, to the point where they would give their life for them. Indeed, in the case of Liet-Kynes, this is indeed what happened. Upon the return of House Harkonnen to Arrakis, Kynes was captured as an accomplice to the Atreides, the Fremen, and witness of the dishonourable ways of the Harkonnens. He was abandoned in the desert without water or a stillsuit, and ultimately killed when heat exhaustion, dehydration and delirium prevented him from escaping a massive spice blow.
Kynes was survived by his daughter, Chani, who later became concubine of Paul. As a result, he was grandfather to the God-Emperor, Leto Atreides II, and his twin sister, Ghanima Atreides. Kynes' descendants continued the terraforming of Arrakis, until it became a lush and fertile world.