[2] He appears to suffer from a verbal tic, but his unusual speech pattern is actually a "humming" code employed to privately communicate with his Bene Gesserit wife Margot.

"[4] Baron Harkonnen refers to Fenring as "Ambassador to the Smugglers", indicating Shaddam IV's interest in spice smuggling operations on Arrakis.

[5] Paul Atreides notes that "Fenring was one of the might-have-beens, an almost Kwisatz Haderach, crippled by a flaw in the genetic pattern—a eunuch, his talent concentrated into furtiveness and inner seclusion.

In Dune, the Harkonnens, secretly aided by the Emperor's fierce Sardaukar warriors, destroy the Atreides forces and reclaim control of Arrakis.

Though Fenring is a failure in the Bene Gesserit breeding program to produce the Kwisatz Haderach, he is a supremely intelligent and perceptive killer.

It is noted in Dune: House Atreides, "Over the years, Fenring had murdered at least fifty men and a dozen women, some of whom had been his lovers, of either sex."

Although Tleilaxu Master Hidar Fen Ajidica manages to create an artificial melange (called ajidamal, or amal) that seems to have the original's properties, it does not work properly.

Disastrously, the first heighliner emerges from foldspace at the wrong point, strikes the defensive shields of Wallach IX and plummets into the atmosphere to its destruction.

All records and laboratories of Project Amal are destroyed by Fenring himself afterward when House Vernius retakes the planet Ix, and Shaddam later denies all knowledge of it.

When Shaddam starts to act without Fenring's counsel due to jealousy, he begins making grievous mishaps, in particular using atomic weapons and a biological plague, and threatening to destroy Arrakis.

This genetic material is used by the Face Dancer Khrone to create a ghola of Paul, named Paolo, as part of the thinking machine plot to dominate humanity.

[11] Paul's concubine Chani uses the poisonous Water of Life to help save him, and he lives; rather than kill the Fenrings, he banishes them to Salusa Secundus into permanent exile with Shaddam, whom they now loathe.